What optic does military use for ar 15?

The primary optic used by the United States military on the M4A1 carbine, which is essentially a variant of the AR-15, is the Aimpoint CompM4 red dot sight. It provides quick target acquisition and good visibility in various lighting conditions.

However, it's essential to note that different branches and units within the military may have specific preferences or utilize various optics based on operational requirements and budgetary constraints. There have been advancements and ongoing evaluations over the years, so some units may also use other optics such as ACOGs (Advanced Combat Optical Gunsights) or more recent holographic weapon sights produced by reputable companies like EOTech.