Clean your AR-15 from the breech to prevent muzzle or chamber damage. Insert into the upper receiver, replacing the bolt carrier, for safe and easy cleaning. Self-centers in the receiver. O-ring seal at breech and solvent port keeps chemicals out of the action. Mfg: Satern SPECS: Machined Delrin. 9 1/2" (24cm) long. Models for AR-15s chambered in .223/5.56mm NATO.