Cut your sight-in time. The X-Ring Boresighter will begin the sight-in process before firing a shot. The laser dot helps a shooter to align the scope or sights with the barrel. This makes the whole sight-in more efficient. Save time and ammunition. Features a positive on / off switch to improve battery life. Allen provides all the fittings you need to make your laser boresighter adapt to almost any gun sized to fit .177 to .50 caliber rifles or 12 and 20-gauge shotguns. The Allen Company X-Ring Laser Boresighter value pack includes a battery and mounting screws for easy assembly.Features: SIGHT-IN SHOOTING: Makes sight-in shooting easy and accurate by providing alignment of your aim with the targets. ACCURACY: Laser features a quick and accurate reset of any sights with the positive on / off switch to improve battery life. FITS: The laser boresighter is easily adaptable fitting .177 to .50 caliber rifles or 12 and 20-gauge shotguns. EASY TO ASSEMBLE: Includes all the tools you need to assemble & mounting screws for complete setup. BATTERY INCLUDED: Pack includes 1 CR2 battery.