Crimson Trace Corporation RailMaster Red Laser and Tactical Light, Universal Rail Mount, Black Finish 01-4250-1 The Rail Master(R) Pro Universal Red Laser Sight & Tactical Light combines two tactical tools in a single compact unit. The versatile unit is designed to fit most modern pistols" rifles and shotguns with an M1913 Picatinny or Weaver-style accessory rail. A powerful red laser anchors the unit and provides up to 2 hours of continuous use on a single CR2 Lithium battery. The Rail Master Pro also includes a powerful 100 Lumen white light for target identification. The unit features four operational modes including: Laser/Light Constant On" Laser Constant On" Light Constant On" and Laser w/Light Dazzler. Activation is instant" with Tap On" Tap Off controls and a programmed Auto Shut Off at five minutes to conserve battery life.