The Angstadt Arms 1/2A-28 Direct Thread Adapter is designed as a universal solution for suppressors that feature a HUB (Hybrid Universal Base) 1.375A-24 thread pitch. This mount allows an ultra low profile direct thread option for your favorite suppressor. Specifications: For HUB thread (1.375A-24) suppressors 1/2A-28 TPI Machined from 17-4 stainless steel with a black nitride finish Weight: 2.5oz 1.55" Diameter Adds just 0.2" to the back of the suppressor This is the same adapter included with all Angstadt Reticent Suppressors, except with a black nitride finish