The Osprey Arbor Kit was designed to make sighting in your guns easier. The boresight is automatically activated when the bolt is closed, then sight to the center of the laser (all calibers differ on sighting distance) recommended 25 yards. This kit includes all of Osprey’s arbors, and a carry pouch. The 223 Green Boresight is used to power all the Arbors. Osprey’s nylon case is used to keep sights clean and dust-free. The industry-leading no-nonsense lifetime warranty backs the boresight/arbor kit.