This a used ARD (American Rifle Depot) barrel. It is 16" long 556 and it has a 1:9 twist. It is stainless steel and spiral Flutted bull barrel. It comes with a B.A.D. Muzzle brake (Thumper) and a B.A.D. Gas block and stainless gas tube.  this an AR-15 barrel. You can call or text me at +15135034314.