12 Gauge Shotgun Laser Bore Cartridge - Fits 12 Gauge Shotguns;Red Laser: 635-655nm， Max output <5mw， Class IIIa Laser;Easy to use， just install the batteries into the Laser cartridge and screw on the base， which turns the laser on. Remove Batteries to turn unit off;Factory Pre-Aligned Cartridge Bore Sighters， helps with Zeroing your optics;Brass Construction.