This is a SilencerCo Mount chambered in 9MM, model AC2447.
The 3-Lug Mount is a quick-attach mounting option for guns with fixed barrels. The 3-Lug Mount must be used with a 3-Lug Muzzle Device. The 9MM 3-Lug Mount must be used only with 9MM 3-Lug Mount Muzzle Devices.
Features:
Quick-attach mounting option
Only use with 9MM 3 lug mount muzzle devices