Donny FL Ronin m20x1 with 1/2”x20 UNF to M20x1 threaded bushing. So it will fit 1/2”x20 or you can remove the adapter and it will fit M20x1. I put plumbing tape on the bushing so it would stay in place in the moderator. There are a couple small nicks that I colored back black with a sharpie, does not affect function. $160 shipped