The Quick Release mount fits all VCOG's, the 1x42 Reflex (w/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 lever system which requires no manual adjustments to attain a proper, rock solid engagement on a 1913 picatinny rail. Distance From Top of Mounting Rail to Optical Axis- 3x, 4x and 5.5x ACOG 1.535", VCOG 1.535" and 1x42 Reflex 1.506".