Allows use of 5/8-24 threaded silencers/muzzle devices on 1/2-28 threaded barrels Machined from 17-4 PH Stainless Steel and heat treated to the H900 condition Only adds .19 to system length 3/4 rear hex fits any standard armorers wrench All threads and critical alignment surfaces CNC machined in one operation to ensure perfect alignment Only .4 ounces