Rearden MFG 10085 R2, 1/2x28 Threads, .375 Bore, Rainbow Finish, Square Shoulder

17-4 PHAtlas and Atlas XL CompatiblePlan B CompatibleAtlas Adapter Overrun Approximately 1.600a ^2Atlas XL Adapter Overrun Approximately 0.750Rainbow Black PVD2.365a ^2 Total LengthThese fit the plan B type mounts. 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.Torque the muzzle device to approximately 30 ft lbs. M