9/16 x 24 tpi barrel thread protector. It is machined from US made steel to very high quality standards on CNC lathes in my shop. It is counter bored to accommodate barrels that are not undercut at the shoulder. Length is .460" Outside diameter is .710 With a clean crisp knurl. Fits Lone Wolf, Storm Lake aftermarket threaded barrels and other brands with a 9/16 x 24 tpi right hand thread. Please confirm your thread size before ordering. Will not fit the factory Glock since it has Metric left hand threads.