This is a Trijicon Adapter known as the Ruggedized Miniature Reflex, model AC32066.
Perfect for that situation where you need the versatility of a magnified optic paired with a Trijicon RMR(R) or SRO(TM) red dot sight in close quarters. This offset rail adapter attaches to the firearm's picatinny rail and provides a short picatinny rail at a 45 degree offset to mount a red dot sight. By mounting a red dot at a 45 degree offset" it allows for an easy transition from the magnified optic by simply rotating the firearm. The low profile of this mount allows you to mount underneath almost any riflescope (such as the Trijicon AccuPoint(R)) without removing the scope or rings" or in front/behind the optic (such as the Trijicon ACOG(R) or VCOG(R)). Please note that this is just the rail adapter. In order to mount the Trijicon RMR(R) or SRO(TM)" you will also need the RM33 Low Mount.
Features:
Aluminum construction
Ambidextrous
Attaches to picatinny rails