This is a Trijicon Mount known as the QR, model AC12033.
This mount fits all VCOG's" the 1x42 Reflex (with ACOG base)" and the 3.5x" 4x and 5.5x ACOG's. The AC12033 quick release mount utilizes a single lever system. It features the patented BLAC(TM) lever system which requires no manual adjustments to attain a proper" rock solid engagement on a 1913 picatinny rail.
Features:
Distance from top rail to optical axis 3x 4x and 5.5x ACOG = 1.535 in. VCOG = 1.535 in. 1x42 Reflex = 1.506 in.
