The Lapco A-5/X7 to Cocker Barrel Adapter allows a A-5/X7 barrel to attach to an Cocker threaded marker. LAPCO Barrel adapters are geared toward the player who just acquired a new marker but can't let go of his/her favorite barrel. Barrel adapters are made of the same high grade aluminum as our barrels. They also feature a killer inner bore that won't interfere with accuracy.