The Megastar  barrel extesion/ flash suppresor  is 1.2 in diameter and 6 inches long with a .5 through hole that will clear up to a .457 caliber round. It comes in 2 differnt versions, one has the thread on the end and will extend the gun the full 6 inches from the shoulder of the thread. The Megastar 3D has the threads recessed 3.0 inchs deep, so it will over lap any barrel 3 inches up to .790 in diameter, and only extend the gun 3.0 inches. The Megastar and Megastar 3D are avaliable in polished, or coated and both 1/2-28 and 5/8-24 threads.