Thread protector blank for gunsmith installation.  This is meant to be installed by a gunsmith while threading the muzzle and contoured to the barrel.  These are a blind front design, meaning that it provides extra crown protection over a standard open front thread protector.  It gives a much cleaner finished appearance also. 1/2-28, 5/8-24 Class 2B threads 1″ Outside Diameter 1/2-28 – 0.400″ 0.001″- 0.000″ Internal Thread Length 5/8-24 – 0.600″ 0.001″ – 0.000″ Internal Thread Length Thread relief at beginning and end of thread 416 Stainless to blend perfectly with barrel steel CNC single point cut threads 1/2-28 – 0.350″ Opening 5/8-24 – 0.440″ Opening * Note that some images show examples of a finished product, the product you receive will be as described above and raw stainless.