Heckler & Koch Barrel, 45 ACP, 5.09, Threaded, Fits USP-T 226349 Spare barrel for USP45 Tactical or upgrade USP45 to accept threaded suppressors or other muzzle attachments. Drop in part for all USP .45 full size" USP 45 tactical pistols (EXCEPT USP45 EXPERT). WILL NOT FIT THE COMPACT MODELS OR THE NEWER HK45 PISTOL