This is a GG&G, Inc. Mount known as the Accucam QD Mount, model GGG-1192. 

With the development of their Accucam Quick Detach Locking Lever System" GG&G is now able to manufacture a full line of QD mounts that allow the primary optic to be attached and detached from the weapons system. This provides the shooter a degree of tactical flexibility highly valued in the urban combat environment. The GG&G Accucam Quick Detach ACOG mount allows the end user the ability to quickly switch between optics and still maintain "on target" repeatability. The Trijicon ACOG is a rugged optic and has an excellent reputation for durability" however should the ACOG fail" end users can quickly remove the ACOG and deploy the weapon's back up iron sight. 

Note about our photos:
While we make every effort to ensure that our product photos are accurate, manufacturers occasionally change the design of components such as triggers, sights, or magazines without notice. Also, modifications to the firearm or component may be required in order to meet specific state compliance requirements. While we make every effort to accurately describe and illustrate the item you are going to receive, there may be visual differences on various components that do not affect functionality.