Field tested and approved by the North American Hunting Club, the Triple Duty universal green laser boresight is designed for sighting in .17 to .50 caliber rifles, shotguns and pistols. A key feature of the device is it doesn't have any additional attachment pieces to be lost. Engineered with a self-cantering 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. Includes a carrying case, (1) CR2 battery, and instructions. Feature: Precision accuracy Reliable and durable Reduce wasted cartridges and shells Compact and lightweight Easy to pack and travel Special retractable arbor for instant centering 15 to 150 yd range for sighting On/off switch operation Visible green laser LED