Finding the best laser rangefinder for hiking and hunting camps requires balancing accuracy, durability, and ease of use. The Leupold RX-1400i TBR/W Gen 2 stands out for its advanced Flightpath technology, ideal for long-range hunting. The Vortex Crossfire HD 1400 offers excellent clarity at a competitive price, making it a versatile choice for campers. Meanwhile, models like the TIDEWE Hunting Rangefinder excel in water resistance and portability for rugged outdoor conditions. Each option involves tradeoffs—higher accuracy often comes with a heftier price, and compact models may sacrifice some range. Keep reading for a detailed breakdown to help you choose the best fit for your outdoor adventures.
Key Takeaways
- Top-tier models like the Leupold RX-1400i integrate advanced ballistic and flight path features for precise long-range measurements.
- Vortex options generally balance affordability with high-quality optics and durable build, suited for versatile outdoor use.
- Rechargeable batteries are common in modern rangefinders, but they require careful maintenance to avoid outages in the field.
- Water-resistant and rugged designs are vital for outdoor camps, especially in unpredictable weather conditions.
- Range capabilities vary widely; choose a model that matches your typical hunting or hiking distances to avoid overpaying for unnecessary range.
| Leupold RX-1400i TBR/W Gen 2 Rangefinder with Flightpath Technology |  | Best Overall for Long-Range Hunting | Model Number: 183727 | Range: Up to 1,400 yards on reflective objects, 1,200 yards on trees | Technology: TBR/W (True Ballistic Range/Wind), Flightpath | VIEW LATEST PRICE | See Our Full Breakdown |
| Vortex Optics Crossfire HD 1400 Laser Rangefinder |  | Best for Versatile Hunting Conditions | Magnification: 5x | Objective Lens: 21mm | Max Range: 1400 yards | VIEW LATEST PRICE | See Our Full Breakdown |
| Vortex Triumph HD 850 Laser Rangefinder |  | Best for Mid-Range Precision and Durability | Range: up to 850 yards | Magnification: 5x | Objective Lens: 21mm | VIEW LATEST PRICE | See Our Full Breakdown |
| Vortex Optics Sonora HD 1800 Laser Rangefinder |  | Best for Extreme Long-Range Precision & Rugged Use | Magnification: 6x | Maximum Range: 1800 yards | Objective Lens: 21mm | VIEW LATEST PRICE | See Our Full Breakdown |
| Vortex Optics Viper HD 3000 Laser Rangefinder |  | Best for Extreme Long-Distance Hunting and Tactical Use | Magnification: 7x | Max Range: 3000 yards | Objective Lens: 25mm | VIEW LATEST PRICE | See Our Full Breakdown |
| CIGMAN Rechargeable Laser Rangefinder 3280 Yards with 6X Magnification and 7 Modes for Hunting, Golf, and Shooting |  | Best Overall for Versatility and Long-Range Accuracy | Range: 5 to 3280 yards | Magnification: 6X | Battery: 750mAh rechargeable, Type-C | VIEW LATEST PRICE | See Our Full Breakdown |
| REVASRI Hunting Laser Rangefinder with Rechargeable Battery, 1000 Yards, Target Acquisition Technology |  | Best Value for Accurate Mid-Range Hunting and Golfing | Range: 5-1000 yards | Magnification: 6.5X | Objective Lens Diameter: 24mm | VIEW LATEST PRICE | See Our Full Breakdown |
| TIDEWE Hunting Rangefinder with Rechargeable Battery, 700/1000Y Camo Laser Range Finder, 6X Magnification, Water-Resistant |  | Best Lightweight and Concealed for Hunting in Various Conditions | Range: 3 to 700 yards | Magnification: 6X | Battery: 750mAh rechargeable Li-ion | VIEW LATEST PRICE | See Our Full Breakdown |
| MILESEEY Hunting Rangefinder, 2000+ Yards Rechargeable Laser Range Finder with Bow Hunting Mode, Waterproof, 7X Magnification |  | Best for Extreme Long-Range Precision in Hunting and Shooting | Range: 2000+ yards | Magnification: 7X | Waterproof: Yes | VIEW LATEST PRICE | See Our Full Breakdown |
| Bushnell Bone Collector 1000 Rangefinder with Angle Range Compensation |  | Best for Bow and Rifle Hunting with Incline/Decline Compensation | Range: up to 1000 yards | Accuracy: 1 yard | Technology: Angle Range Compensation (ARC) | VIEW LATEST PRICE | See Our Full Breakdown |
More Details on Our Top Picks
Leupold RX-1400i TBR/W Gen 2 Rangefinder with Flightpath Technology
The Leupold RX-1400i TBR/W Gen 2 stands out for its advanced ballistic calculations and Flightpath technology, making it the top choice for hunters who need precise long-distance readings. Compared to the Vortex Viper HD 3000, it offers more sophisticated trajectory data, though it comes at a higher price and with a steeper learning curve. This model’s bright, adjustable red display improves readability in varying light conditions, which is essential in field conditions. Its durable, lightweight housing ensures it can withstand rugged environments without adding unnecessary weight. While its complex features provide accuracy benefits, they may overwhelm casual users or those new to rangefinders. Battery life details are not specified, which could be a concern during extended trips. This pick is ideal for experienced hunters or long-range shooters who prioritize precision and advanced features, but less so for casual users seeking simplicity.
Pros:- Highly accurate ballistic range calculations for long-distance shots
- Bright, adjustable red display enhances readability in diverse lighting
- Lightweight yet durable for rugged outdoor use
- Includes advanced Flightpath technology for archery and long-range shooting
Cons:- Expensive compared to simpler rangefinders
- Features may require time to learn and master
- Battery life not specified, risking potential power issues in extended use
Best for: Serious hunters and long-range shooters needing precise ballistic data
Not ideal for: Beginners or casual users who prefer straightforward, plug-and-play devices
- Model Number:183727
- Range:Up to 1,400 yards on reflective objects, 1,200 yards on trees
- Technology:TBR/W (True Ballistic Range/Wind), Flightpath
- Display:TOLED, adjustable brightness
- Housing Material:Polymer
- Batteries Included:Yes
- Weight:Lightweight
Bottom line: This rangefinder is best suited for experienced hunters focused on long-range precision and advanced ballistic features.
Vortex Optics Crossfire HD 1400 Laser Rangefinder
The Vortex Crossfire HD 1400 offers a reliable 1,400-yard maximum range with 5x magnification, making it a solid choice for hunters who need versatility in various terrain. Its HD optical system ensures clear images, even in low-light conditions, surpassing some basic models like the TIDEWE 700/1000Y in image clarity. The waterproof and shockproof construction adds durability, making it suitable for tough outdoor environments. Its target modes—Normal, First, Last—provide flexibility for different hunting scenarios. However, it lacks some of the advanced ballistic features found in the Leupold RX-1400i, so it’s less ideal for long-range precision shooting. Batteries are required, but details are not specified, so long trips could pose a power concern. This device is well-suited for hunters who want reliable, straightforward rangefinding in varied conditions but might not satisfy those seeking advanced ballistic features.
Pros:- Maximum range of 1,400 yards for versatile hunting needs
- HD optical system offers clear, bright images
- Waterproof and shockproof build for rugged outdoor use
- Lightweight at 4.8 ounces for easy carry
Cons:- Lacks advanced ballistic or trajectory features
- Batteries needed, with no specified lifespan
- Limited to basic rangefinding functions
Best for: Hunters needing a durable, easy-to-use rangefinder across diverse terrain
Not ideal for: Long-range shooters or archers requiring detailed ballistic data
- Magnification:5x
- Objective Lens:21mm
- Max Range:1400 yards
- Target Modes:Normal, First, Last
- Ranging Modes:HCD, LOS
- Waterproof:Yes
Bottom line: This rangefinder provides dependable performance for hunters in need of a durable and straightforward device for various conditions.
Vortex Triumph HD 850 Laser Rangefinder
The Vortex Triumph HD 850 offers excellent distance measurement up to 850 yards on reflective targets, making it perfect for hunters focused on mid-range accuracy. Its high-definition optical system, combined with multiple modes—LOS, HCD, Scan—delivers versatile readings, comparable to the Vortex Crossfire HD 1400, but with a more limited maximum range. Its waterproof and shockproof design, along with a lifetime VIP warranty, emphasizes durability in outdoor environments. While it excels in clarity and build quality, its range is less suited for long-range shooting, and it does not include advanced ballistic features. The price point may be higher than basic models, but the lifetime warranty provides long-term value. This pick makes sense for hunters who need reliable mid-range performance combined with robustness.
Pros:- Accurate up to 850 yards on reflective targets
- High-definition optical system delivers crisp images
- Durable, waterproof, and shockproof for tough outdoor use
- Includes lifetime VIP warranty for peace of mind
Cons:- Limited to 850 yards maximum range
- More expensive than entry-level models
- Lacks advanced ballistic features
Best for: Hunters seeking high-quality optics for moderate distances with durable build quality
Not ideal for: Long-range shooters or those requiring extensive ballistic calculations
- Range:up to 850 yards
- Magnification:5x
- Objective Lens:21mm
- Modes:LOS, HCD, Scan
- Waterproof:Yes
- Warranty:Lifetime VIP
Bottom line: This device suits hunters who want high-quality optics and durability for mid-range hunting scenarios.
Vortex Optics Sonora HD 1800 Laser Rangefinder
The Vortex Sonora HD 1800 is designed for serious long-distance hunters, measuring up to 1,800 yards on reflective targets. Its 6x magnification and HD optical system deliver sharp images across challenging lighting conditions. The fully multi-coated lenses and ArmorTek coating ensure durability and clarity, even in harsh environments. Its HCD (Horizontal Component Distance) technology adds precise angle compensation, essential for accurate shots on uneven terrain. While its high maximum range beats most competitors like the Crossfire HD 1400, its higher price and bulkier build might deter casual users or those with tight budgets. The device’s tripod adaptability enhances measurement stability, but battery life details are not clear, which could impact extended trips. This model is best for experienced long-range hunters needing rugged reliability and maximum distance capability.
Pros:- Maximum range of 1,800 yards on reflective targets
- HD optical system ensures clear images in all conditions
- Rugged, waterproof construction with scratch-resistant coatings
- Tripod adaptable for stable readings
Cons:- Higher price point compared to shorter-range models
- Bulkier size may reduce portability
- Battery lifespan information is unclear
Best for: Long-range hunters and shooting enthusiasts demanding maximum distance and rugged durability
Not ideal for: Casual hunters or those primarily seeking mid-range, lightweight devices
- Magnification:6x
- Maximum Range:1800 yards
- Objective Lens:21mm
- Technology:HCD angle compensation
- Waterproof:Yes
- Warranty:Unlimited, lifetime
Bottom line: This rangefinder is tailored for long-distance hunters who need maximum range and rugged reliability in challenging environments.
Vortex Optics Viper HD 3000 Laser Rangefinder
The Vortex Viper HD 3000 offers an impressive maximum range of 3,000 yards, making it ideal for hunters and shooters who require ultra-long-distance capabilities. Its 7x magnification and HD optics provide sharp, bright images, even in low-light conditions. Multiple target and ranging modes, including ELR (Extended Long Range), extend its versatility beyond basic rangefinding. Its waterproof and shockproof design ensures durability in rugged outdoor settings, matching the needs of serious long-range enthusiasts. However, the absence of specific weight details and the high price point may be limiting factors for some buyers. The device requires a CR123 battery, which might be an inconvenience for extended trips without spares. This rangefinder is best suited for long-distance shooters and tactical professionals who prioritize maximum range over portability.
Pros:- Unmatched maximum range of 3,000 yards
- HD optics for crisp, clear images in all conditions
- Waterproof and shockproof design for durability
- Multiple ranging modes including ELR
Cons:- Weight details are not provided, potentially affecting portability
- Higher cost may be prohibitive for some users
- Requires CR123 batteries, which may need frequent replacement
Best for: Long-range hunters and tactical shooters demanding maximum distance and rugged durability
Not ideal for: Casual hunters or those seeking lighter, more affordable options
- Magnification:7x
- Max Range:3000 yards
- Objective Lens:25mm
- Target Modes:Normal, First, Last, ELR
- Waterproof:Yes
- Battery:CR123
Bottom line: This device is perfect for long-distance shooters and tactical operators needing maximum range and rugged dependability, despite its higher price and size.
CIGMAN Rechargeable Laser Rangefinder 3280 Yards with 6X Magnification and 7 Modes for Hunting, Golf, and Shooting
This CIGMAN rangefinder stands out for its extraordinary measurement range of up to 3280 yards, making it ideal for hunters covering large terrains or long-distance shooters. Compared with the MILESEEY, which offers over 2000 yards, the CIGMAN’s extended range and multiple modes—including slope and speed—add a layer of precision that benefits serious outdoor enthusiasts. Its rechargeable battery supports thousands of uses, but this could become a downside for those who prefer simplicity, as managing multiple modes might be overwhelming for casual users. The waterproof and dustproof build ensures durability in rugged conditions, yet the complex interface demands a learning curve for newcomers. If you need a highly adaptable, long-range device with advanced features, this pick delivers, but it’s less suited for quick, straightforward measurements. It’s best for experienced hunters or shooters who value extensive functionality over simplicity.Pros:- Ultra-long measurement range up to 3280 yards
- Multiple modes including slope, speed, and flagpole lock
- Rechargeable battery with high usage capacity
- Waterproof and dustproof for tough outdoor conditions
Cons:- Battery capacity may require frequent recharging during heavy use
- Complex mode interface can be confusing for casual users
Best for: Experienced hunters and shooters needing maximum range and multi-mode versatility
Not ideal for: Casual users or those who prefer straightforward operation without extensive mode options
- Range:5 to 3280 yards
- Magnification:6X
- Battery:750mAh rechargeable, Type-C
- Battery Life:up to 6000 uses per charge
- Modes:7 modes including slope, speed, scan, flagpole lock
- Waterproof:Yes
Bottom line: Best suited for advanced users seeking extensive features and maximum range in demanding outdoor environments.
REVASRI Hunting Laser Rangefinder with Rechargeable Battery, 1000 Yards, Target Acquisition Technology
The REVASRI rangefinder offers precise measurements up to 1000 yards, making it a reliable choice for both hunting and golfing. Its 6.5x magnification and clear optics outperform some budget options, but it falls short of the extended range offered by the CIGMAN or MILESEEY. Its multiple modes—including target locking and scanning—provide versatility, though this complexity might require some initial learning. The compact, weather-resistant design makes it convenient for outdoor use, yet it lacks some connectivity features like Bluetooth or app integration found in higher-end models. This device makes the most sense for users who want reliable accuracy at a reasonable price without the need for extreme long-range measurement. If you primarily hunt or play golf within 1000 yards, this model fits well, but it’s less suitable for long-distance shooting.Pros:- Accurate up to 1000 yards with clear optics
- Multiple modes including target locking and scanning
- Rechargeable, portable design
- Weather-resistant for outdoor use
Cons:- Limited to a maximum of 1000 yards range
- May have a learning curve for mode operation
- Lacks advanced connectivity features
Best for: Hunters and golfers seeking accurate measurements up to 1000 yards with easy portability
Not ideal for: Long-range shooters or users needing more than 1000 yards measurement capability
- Range:5-1000 yards
- Magnification:6.5X
- Objective Lens Diameter:24mm
- Battery:Built-in lithium rechargeable
- Accuracy:+/- 1 yard
- Size:96mm x 34mm x 67mm
Bottom line: A solid mid-range choice for hunters and golfers who prioritize accuracy and portability over extreme distance measurement.
TIDEWE Hunting Rangefinder with Rechargeable Battery, 700/1000Y Camo Laser Range Finder, 6X Magnification, Water-Resistant
The TIDEWE rangefinder is designed for hunters who value concealment and ease of use, offering measurements up to 700 yards—adequate for most hunting scenarios. Its 6X magnification and camouflage pattern help it blend into natural environments, making it ideal for stalking game. Compared with the REVASRI, which reaches 1000 yards, the TIDEWE’s shorter range limits its use for open terrains, but it compensates with a lighter, more ergonomic design. The rechargeable battery supports extended use, though some may find the control layout initially complex. Its IP54 water resistance ensures durability in unpredictable weather, yet it’s less suited for long-range shooting or large open-area hunts. This model works best for hunters focused on close to mid-range game in varied conditions, especially where weight and concealment matter.Pros:- Lightweight and ergonomic for easy carry
- Camouflage pattern enhances concealment
- Rechargeable with long lifespan
- Water resistance for outdoor durability
Cons:- Maximum range limited to 700 yards
- Controls may seem complex initially
- Less suited for open terrain or long-distance shooting
Best for: Hunters who prefer a lightweight, camo device for up to 700 yards in mixed terrain
Not ideal for: Long-range hunters or users needing measurements beyond 700 yards
- Range:3 to 700 yards
- Magnification:6X
- Battery:750mAh rechargeable Li-ion
- Dimensions:4.12 x 2.61 x 1.50 inches
- Water Resistance:IP54
Bottom line: Ideal for hunters prioritizing concealment, portability, and mid-range accuracy in varied environments.
MILESEEY Hunting Rangefinder, 2000+ Yards Rechargeable Laser Range Finder with Bow Hunting Mode, Waterproof, 7X Magnification
The MILESEEY rangefinder excels in offering over 2000 yards of measurement capability, surpassing most competitors like the REVASRI in maximum distance. Its 7X magnification provides a clearer view of distant targets, making it suitable for open terrain hunting or long-range shooting. The waterproof, impact-resistant design ensures durability in tough conditions, but the weight isn’t specified, which could pose portability issues for extended hikes. Its advanced features, including multiple targeting modes, mean a steep learning curve for beginners, and the price point isn’t listed, potentially limiting accessibility. For hunters or shooters needing unmatched long-distance precision and durability, this model offers a compelling choice; however, it’s less practical for those focused on lightweight gear or shorter-range activities.Pros:- Maximum range over 2000 yards
- High magnification of 7X for detailed viewing
- Waterproof and impact-resistant for tough outdoor use
- Multiple targeting modes for versatility
Cons:- Weight may be bulky for long hikes
- Complex features require learning time
- Price information is not provided
Best for: Experienced hunters and long-range shooters requiring over 2000 yards measurement and rugged build
Not ideal for: Casual hunters or those involved in quick, close-range shooting scenarios
- Range:2000+ yards
- Magnification:7X
- Waterproof:Yes
- Battery:USB-C rechargeable
- Impact Resistance:Yes
Bottom line: Best suited for advanced users demanding extreme range and rugged durability in demanding environments.
Bushnell Bone Collector 1000 Rangefinder with Angle Range Compensation
The Bushnell Bone Collector 1000 offers precise distance measurement up to 1000 yards with 1-yard accuracy, making it ideal for hunters using bows or rifles on varying terrains. Its ARC technology provides true horizontal distances on inclines and declines, a feature that makes it stand out over simpler models like the TIDEWE, especially in hilly environments. The bright optical system ensures clear visibility in low-light conditions, and the rapid scan speed allows quick target acquisition. However, it’s priced higher than basic models, and its learning curve might challenge newcomers unfamiliar with advanced optics. This rangefinder suits serious hunters who prioritize accuracy in complex terrains, though casual users or those hunting in flat areas may find it less necessary.Pros:- Accurate up to 1000 yards with 1-yard precision
- Advanced ARC technology for true horizontal distances
- Bright optical system for low-light conditions
- Fast scan speed for quick readings
Cons:- Higher cost compared to basic models
- Requires familiarity with advanced features
- Limited to hunting and shooting applications
Best for: Hunters using bows or rifles on hilly ground needing accurate slope-adjusted distances
Not ideal for: Casual hunters or those in flat terrain who don’t need angle compensation
- Range:up to 1000 yards
- Accuracy:1 yard
- Technology:Angle Range Compensation (ARC)
- Brightness:Up to 2X brighter images
- Scan Speed:4 times per second
Bottom line: Ideal for serious hunters requiring precise, slope-adjusted distances in variable terrains.
How We Picked
Our evaluation focused on performance, durability, ease of use, and value. We prioritized range accuracy, especially at typical outdoor distances, and assessed how user-friendly each model is in field conditions. Build quality and water resistance were critical factors, as outdoor environments demand ruggedness. We also considered battery life and maintenance needs, ensuring that the rangefinders are reliable during extended trips. Products were ranked based on a balance of these factors, with the best overall picks excelling in multiple areas for versatile outdoor use.Factors to Consider When Choosing Best Laser Rangefinder For Hiking And Hunting Camps
Choosing the right laser rangefinder for hiking and hunting camps involves understanding several key factors. Beyond raw range, aspects like ease of handling, durability, and technological features can significantly impact your experience. Making an informed decision means weighing what matters most for your specific outdoor activities, whether it’s long-distance accuracy or rugged construction. Here are the main considerations to keep in mind before purchasing.Range and Accuracy
The primary function of a rangefinder is to measure distances accurately. For camping and hunting, consider how far you typically need to measure—models with a range of 1000 yards are usually sufficient for most hunting scenarios. Higher range capabilities tend to come with increased cost and bulk, but they offer more flexibility for open terrain. Keep in mind that accuracy can vary with environmental conditions like fog or rain, so look for models with good performance in adverse weather.
Durability and Weather Resistance
Outdoor environments demand robust construction. Water resistance, fog-proofing, and shockproofing are essential features that prevent damage during rough use. A rangefinder that’s not water-resistant risks malfunctioning when rain or snow hits, which can ruin a trip. Prioritize models with durable casings and sealed lenses if you expect to encounter harsh weather conditions frequently.
Ease of Use and Readability
In the field, simplicity counts. Look for a rangefinder with clear, bright optics and an easy-to-read display. Features like one-button operation and ergonomic design help conserve energy and reduce frustration during quick measurements. Some models include scan modes or multiple targeting options, which can be useful but may add complexity if you prefer straightforward operation.
Additional Features and Technology
Modern rangefinders often incorporate ballistic calculators, angle compensation, or target priority modes. These features can greatly improve accuracy, especially when shooting or estimating distances on uneven terrain. However, more advanced tech usually increases price and complexity. Decide which extras genuinely enhance your experience rather than complicate it unnecessarily.
Battery Life and Maintenance
Extended trips require reliable power sources. Rechargeable batteries are convenient but need proper care, while standard batteries are more straightforward but may run out unexpectedly. Consider models with battery indicators or easy access to replace batteries. Preventative maintenance, like cleaning lenses and storing the device properly, can extend the lifespan of your rangefinder.
Frequently Asked Questions
How important is range for hiking and hunting camps?
Range is a critical factor because it determines how far you can measure accurately in open terrain. For most hunting and hiking scenarios, a range of 1000 yards is sufficient, but if you’re planning long-distance shots or measuring across large open areas, consider models with extended range capabilities. Remember, longer range often means higher cost and larger size, so match the range to your typical outdoor needs rather than opting for the maximum available.
Should I prioritize water resistance over optical quality?
Both features are important, but water resistance should take precedence if you often encounter rain, snow, or muddy conditions. A water-resistant design protects your device from damage, ensuring longevity in rugged environments. Optical quality directly impacts your ability to see details clearly, so aim for a model that balances both. A highly durable, water-resistant rangefinder with decent optics often beats a fragile, clearer one that could fail in the field.
Are rechargeable batteries worth it for outdoor use?
Rechargeable batteries can be very convenient, especially if you frequently use your rangefinder. They reduce ongoing costs and are environmentally friendly, but they require a proper charging routine and can fail if not maintained well. For extended trips where charging options are limited, models with replaceable standard batteries might be more reliable. Weigh your typical usage patterns and trip length before choosing between rechargeables and disposable batteries.
What features are most useful for beginner hunters or hikers?
Beginners benefit from straightforward operation and reliable accuracy. Look for models with simple one-button controls, clear displays, and basic distance measurement without complicated settings. Features like angle compensation or ballistic calculators can be overwhelming initially, so prioritize ease of use. Durability and water resistance are also vital, ensuring the device withstands rough handling and weather conditions without fuss.
How much should I expect to pay for a good outdoor laser rangefinder?
Quality models suitable for hiking and hunting typically range from $150 to $500. Lower-priced options often lack advanced features or durability, while premium models provide longer range, better optics, and rugged construction. Consider your actual needs—if you’re a casual hiker, a budget-friendly model might suffice, but dedicated hunters or long-range shooters should invest in a more capable, higher-priced device to ensure accuracy and longevity.
Conclusion
For general outdoor use, the Leupold RX-1400i offers a reliable combination of range, accuracy, and durability, making it the best overall choice. Budget-conscious hikers and hunters will find the Vortex Crossfire HD 1400 provides excellent value with solid performance. For those seeking premium features and top-tier build quality, the Vortex Triumph HD 850 or MILESEEY 2000+ Yards Rangefinder are worth considering. Beginners should prioritize models with simple controls and good durability, while experienced users might invest in higher-range, feature-rich options to maximize accuracy and versatility in demanding environments. Your ideal pick depends on your specific outdoor activities and budget constraints.
