Rearden MFG RPB Rainbow PVD Muzzle Brake .280 1/2-28 Black Rainbow PVD. Always use an alignment rod to ensure that the entire system is set up correctly. Make sure all surfaces are cleaned and the muzzle device has been torqued and Rockset to the barrel. Use on a Q can voids your warranty be warned. Specifications for Rearden MFG RPB Rainbow PVD Muzzle Brake: Manufacturer: Rearden MFG Color: Black Rainbow Finish: PVD Package Contents: Rearden MFG RPB Rainbow PVD Muzzle Brake Shims Rearden MFG 10055: RPB Rainbow PVD Muzzle Brake .280 1/2-28 Black Rainbow PVD