This is a GG&G, Inc. Mount, model GGG-1002.
These two GG&G optical mounting rails were designed to mount easily over the integral rails of the AR-15/M16 flat top receiver and work in conjunction with any of GG&G's back up iron sights. The rails mounting brackets raise the line of sight by 1/2 inch" to offer a proper cheek weld when optical devices are attached. In addition" they serve to protect the flat top receiver's integral rails from the damaging wear associated with lever type quick-release mounts" especially those without buffer pads. The Standard Rail is employed mainly as a riser for conventional optical sights. When mounted with a GG&G back up iron sight" it is flush with the end of the receiver.
Features:
Raises line of sight ½ inch
Mount is 5 inches long
Made from solid billet 6061-T6 aluminum alloy
Type III hard coat anodized matte black finish