This is a Bravo Company Mount known as the KeyMod, model BCM-1913LM-KM.
Bravo Company's BCM GUNFIGHTER Modular Light Mount KeyMod is used with 1913 Mounted Lights. It is fully ambidextrous and made to mount flush or cantilever off either the left or right side of the rail system. It has optional high and low mounting positions for the 1913 rail section and it fits most common 1913-rail/pistol/weapon light systems. There are multiple mounting holes for ideal placement and is designed to mount on the 3 or 9 o'clock positions. Its durable aluminum construction is intently designed to be low-profile and snag free.
Features:
Comes with Torx wrench
For 1913 Mounted Lights-KeyMod version