These are designed for Plan B type bipods. Always use an alignment rod to ensure the system is assembled correctly. Clean all surfaces and ensure the muzzle device is torqued to 30 ft-lb and Rockset to the barrel. Be aware that using a Q can will void your warranty. When installing the muzzle device, make sure it is square to the shoulder. For the silencer, clean the threads and tapers before attachment. Torque the suppressor to 10 ft-lb and ensure proper alignment. The nitride finish helps create a tighter seal, but proper torque and Rockset application are essential for optimal performance. Engineered for barrels exceeding 3/4 inches in diameter, yet compatible with smaller barrels as well 17-4 PH H900 with a black nitride finish Compatible with Atlas and Atlas XL Compatible with Plan B The Atlas adapter has exceeded its limit by approximately 1.05 inches Atlas XL adapter does not experience overrun