Must have if you're locked into the pin and weld huxwrx system that comes on geissele uppers - HUXWRX HUB QD Adapter 2.0

Only got this because the .812 556 Geissele upper I recently got from here had the huxwrx qd flash hider on it pinned and welded. Looks like I'm locked into the huxwrx mounting system now as this was my first purchase since getting my first suppressors. Hopefully it holds up. Be warned though, if you don't used a tool to really tighten this thing down, it will start to come loose every 50-100 rounds. Both my brother and I are above average size and strength, especially hand/grip strength, and we could not get this thing to stay mounted tightly during a ~500 round range day. Had to retighten it several times during the range trip last weekend. When I got home I added a wrench to the range bag and snugged this thing down slightly tighter than I can get with my hand. We'll see how it performs the next time out.