Field tested and approved by the North American Hunting Club, the Sightmark Triple Duty Universal Green Laser Boresight is designed for sighting in .17-.50 caliber rifles, shotguns, and pistols. A key feature of the device is that it doesn't have any additional attachment pieces to be lost. Engineered with a self-centering arbor, the unit attaches into the end of the barrel as opposed to the inside, preventing metal from protruding into the Firearm barrel. Simply place the base of the bore sight onto the end of the barrel, and it will attach magnetically. It includes a carrying case, one CR2 battery, and instructions.