The STG 77 was one of the first general issued service rifles to come equipped with a magnified optic from the factory. Regardless of unit or role every soldier who was issued an STG 77 received a 1.5x magnified optic as opposed to the iron-sights so commonly issued in the day. The factory STG 77 optic is designed to be virtually identical to the original integrated optic of the very first AUG and is the closest you can get to owning an original AUG A1. The modern STG 77 optic retains the original profile back-up iron-sights and weight of the AUG A1 integrated optic with a few upgrades. The 'Donut' reticle has received an additional pin-point center dot to allow for more accurate aiming at range and the support struts have gotten slight buttressing to increase durability. If you want to own a piece of history the STG 77 factory optic is a must have. - This is the FACTORY 1.5 X optic that integrates onto the A3 M1 receiver ONLY. Can be easily switched out with the offered rail versions of the A3 M1 via three 4MM hex head bolts. Blue thread locker is used but bolts can be removed with minimal force.