The Method Dynamics Jet Drive Dual Port Muzzle Brake reduces felt recoil and is also threaded to accept Plan B suppressor mounts. Features17-4 PH900 Stainless SteelCompatible with all Plan B Muzzle DevicesIncludes Shims Note: The use of suppressor grease on all Plan B muzzle device to Plan B/HUB suppressor adapters to prevent carbon lock seizing. Failure to use grease will void limited lifetime warranty.