The Crimson Trace Rail Master CMR-201 is a powerful and versatile red laser sight engineered to fit virtually any rail-equipped pistol, rifle, or shotgun. Locking securely onto Picatinny M1913 or Weaver-style accessory rails via Crimson Trace's Secure-Lock Technology, the CMR-201 will not shift under recoil or handling once installed. The unit features ambidextrous tap-on/tap-off activation controls for instant laser deployment from either side, along with a convenient 5-minute auto-shutoff to conserve battery life if inadvertently left on. Powered by a single included 1/3N Lithium battery with over four hours of continuous runtime, the CMR-201 is factory sighted at 50 feet and is fully user-adjustable for windage and elevation. Four custom-fit inserts are included to fine-tune the rail fit across a wide range of platforms — including Glock, Ruger, Sig Sauer, Smith & Wesson, Springfield Armory, Walther, and more — making the CMR-201 one of the most adaptable laser sights on the market. Crimson Trace Rail Master CMR-201 5mW Green Laser for Picatinny & Glock Rails, Ambidextrous Controls Adjustable Windage/Elevation 01-3000227