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".Type: 1-Piece BaseModel: Quick Release Mount ACOGStyle: Locking Quick ReleaseFinish: BlackMaterial: AluminumPieces: 1Mount Type: Picatinny RailMount Height: 1.51" - 1.54"