Easy to install The red laser viewfinder has three screw holes, and you only need to select one hole to screw the viewfinder to the perfect position on a standard guide rail that is 21mm wide (the gap between the guide rail screw slot and the trigger protection should be greater than 0.9 inches) [Bright Red Beam] A bright and accurate red laser sight with a safe beam intensity/wavelength of<5mW peak, 532nm, IIIA level. Highly visible red laser, suitable for any environment from 50 to 100 feet [User friendly] Convenient for left and right handed users to activate with both hands. The laser viewfinder is made of fiber-reinforced nylon, ultra compact, lightweight, and only 1.41 ounces (including battery) Rechargeable Battery The red laser viewfinder is powered by a built-in rechargeable battery and charged through a USB-C cable. The red beam laser can operate for 5 hours [Powerful and precise] Low pose red laser sight, compatible with standard Picatinny rails. Slowly and interactively adjust the elevation and wind speed using the included internal hex wrench. Adjustable wind speed and elevation settings can help improve accuracy (one-way adjustment may lock or damage threads)