TPM (Thread Protector, Muzzle devices) for 0.900 x 24 threaded muzzle devices / suppressor mounts such as Plan B, Rearden Manufacturing, Liberty Precision Machine flash suppressors comps and brakes, etc.. Two versions are available: TPM-F (with wrench flats), and TPM (sans wrench flats) Machined from solid bar stock in 4140 steel and black nitrided, TPM has widely spaced flutes to assist installation and removal. TPM-F has wrench flats for a 7/8 wrench for when the thread protector refuses to budge by bare hands. Proudly designed and made in USA