This is a Trijicon Red Dot known as the MRO, model MRO-C-2200031.
The Trijicon MRO(R) (Miniature Rifle Optic) is a sealed miniature reflex sight intended for use on rifles" carbines and shotguns to provide fast target acquisition. The large aperture and tapered light path maximizes the viewing area and allows for better situational awareness and fast target engagement - especially from non-standard shooting positions. Combine all this with the ambidextrous brightness controls" sub-flush adjusters" advanced lens coatings and the fully sealed" waterproof" hard anodized forged 7075-T6 housing and you have the ultimate mini reflex sight on the market.
Features:
Adjustable brightness
Easy to set adjusters
Surface flush adjusters
Waterproof to 30M
Single Lithium battery