This quick and convenient laser bore sight helps dial in a new scope or sight set without wasting expensive ammunition at the range. It features a patented design that can be used on the muzzle of 17 to 50 caliber firearms. The laser is powered by three LR44 batteries (included) and comes with assorted O-rings for the perfect fit while eliminating metal on metal contact that can scratch your gun and even damage rifling. Includes carrying case and calibrated alignment target. DX models include 12 and 20 gauge adapters for sighting in shotguns.