I bought a Surefire flash hider and a Tapco armorers wrench and the wrench was too small to fit over the flash hider. So I bought a Wheeler armors wrench and that was too small as well. The gunsmith at the LGS said that Surefire has a proprietary size flash hider and that I would have to pay him to install it. I would rather do it my self so what wrench do I need?