The GRL 500 HCK Self-Leveling Rotary Laser Kit features a fully automatic grade (slope) function with Center Line Mode that delivers automatic positioning on benchmark. Integrated Lithium-Ion rechargeable batteries in both the rotary laser unit and receiver offer best-in-class operating times. Included is a detachable receiver that can give you status, settings and measurements while separated from the unit. A built-in safety feature automatically locks the tool when the receiver is removed for theft deterrence. The working range for device extends up to 1,650-Feet.