I have tested it with my ZParts Ops 12th Suppressor and it is 100% compatible. I only disliked the aluminum barrel piece because it was pure black and it looked so fake. So, if you need a suppressor and the VFC Ops 12th Suppressor is out of stock, buy this set and it is also compatible with the barrel of the VFC Mk12 Mod 1 SPR Upper Set GBB Rifle.