This in-Chamber 12 Gauge Shotgun Red Laser Bore Sight is heavy duty and casing is made from solid brass. The 12 gauge shotgun laser bore sight features a Class IIIA red laser <5mW. Simply chamber the bore sight like a regular 12 ga shotgun shell and a laser dot will show exactly where the rifle is aiming, its easy to sight in any scope without firing a single shot. Live fire is only needed to fine tune the weapon being sighted in order to compensate for inconsistencies, such as bullet drop due to distance. Takes 3 AG13 Batteries included.