NCStar's Red Laser Sight with Universal Barrel Mount features a tri-rail universal barrel mount which is compatible with most standard rifle barrel diameters. Constructed of aluminum and plastic the laser has a 635-655nm wavelength with a 5mW output and a side to side toggle on/off switch. It uses and includes two AG13 batteries and mounting tools. Features: Tri-rail universal barrel mount will fit most standard rifle barrel diameters Side to side toggle on/off switch Includes mounting tools International orders will not include batteries