This is a Midwest Industries Sight known as the Combat Rifle Sight, model MI-CRS-OSS.
The Midwest Industries 45 degree offset combat rifle sights for AR15 platform firearms and other continuous rail platforms offer convenient" reliable sights that are ready when you need them and completely out of the way when you don't. Constructed of lightweight 6061 aluminum" these sights are fully ambidextrous" and can be installed to the left or the right side of the firearm.
Features:
Front offset sight is low profile uses a standard A2 front sight post has dual locking detent springs and 1.5 MOA per click adjustments
Rear offset sight is low profile has intermediate aperture dual locking detent springs and Rifle .5 MOA / Carbine .65 MOA click adjustments
