The IWI HUB+ mounting system is an enhancement of the universally recognized HUB (1.375A-24) rear thread pattern. The inclusion of a taper surface for greater engagement between mount and silencer provides for a rock-solid attachment and the best efficiency and consistency for the muzzle and suppressor interface. IWI Silencers are reverse compatible with existing HUB systems. Features: Materials:: 4140 Nitrided Steel Weight: 3.5 oz Muzzle Attachment: Direct Thread Color: C-Series Cerakote Black Full-Auto Rated: Yes