This adapter makes surefire muzzle devices compatible with 1.375×24 threads or 1-7/16×20 threads. This adapter starts out as a surefire warden that is cut and internally threaded for our titanium adapter piece. The adapter piece is mated to the internally threaded surefire warden using high temp Loctite to ensure a rock solid fitment. The adapter adds 2.1″ to the OAL, and allows adequate clearance for most surefire muzzle devices. These adapters are available in both FDE and matte black. These adapters are made to order so expect 1-3 week lead times.