Cut 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. Features a positive on/off switch to improve battery life. The Allen Company X-Ring Laser Boresighter value pack includes a battery and mounting screws for easy assembly. *Sized to fit .177 to .50 caliber rifles, or 12 and 20-gauge shotguns