The Primary Arms Micro Dot Mount allows the user to mount any Micro Dot Red Dot Sight to an AR-15 or similar platform. The light weight design, constructed of anodized aluminum, is easy to install. Absolute Co-Witness- When looking down the iron sights, the red dot will be placed in the middle of the Micro dot's scope tube (optical height of 1.5") Lower 1/3 Co-Witness- When looking down the iron sights, the red dot will be placed in the bottom part of the Micro dot's scope tube (optical height of 1.65"). This allows for a less obstructed view of the entire scope tube when using the red dot instead of the iron sights.