Rear Sight Laser (RSL) for Ruger's model 10/22 rifle. The RSL's ground-breaking new laser design incorporated into the rear sight, compact size and revolutionary performance make it the most extraordinary system LaserLyte has produced. Easy-to-install and easy-to-operate, the new RSL offers a high-power laser with the benefit of not having to replace existing grips or internal stock parts. The RSL's activation switch is a strategically placed button at the back of the laser that is easily activated. First press of the activation switch produces the constant on mode, second press produces pulse mode, and third press deactivates the laser. A small LED on the back of the laser indicates if the laser is on and what mode it is in. This RSL fits Ruger 10/22 rifles with rear dove tail sights. The body is constructed from MIM 4650, nickel enriched high carbon steel, the same material used for most heavy-duty gun parts such as iron sights, hammers and levers. The laser body is precision mounted to a proprietary adapter made of 1018 steel, low carbon mild steel. It is also black chrome, bead blasted for a non-reflective finish. When mounted onto the pistol the RSL will fit all Level I and II holsters. The RSL is powered by four 377 batteries that provide six hours of normal usage. Normal usage is defined as one minute on and one minute off. This test mimics actual usage where the unit is turned on and off and the battery is given time to automatically regenerate. The RSL is tested and recommended by the National Tactical Officer's Association.