I've seen thread on, bolt on, strap on, quite a few companies making them. In my scenario I'm looking at predators/varmints with 6mm 6.5 and 7mm bores, I'm not interested in true subsonic, just looking to reduce the report and recoil if feasible. None of my muzzles are currently threaded, but that can be remedied if that's best. The 7mm is a magnum if that matters, I really know VERY little about requirements for effectiveness, but I do understand the legal aspects surrounding them. I just want to know what the best options are.