The Patent Pending Arisaka Aimpoint Acro Mount Mk2 is designed for the Aimpoint Acro P1 and P2 optics, and will also function with other red dots using the same footprint. The Arisaka Aimpoint Acro Mount Mk2 is available in 1.54", 1.93", and 2.26" heights. 1.54" is considered lower 1/3 co-witness, meaning standard AR height iron sights are visible in the lower 1/3 of the red dot optic lens. 2.26" matches up with the Unity FAST FTC Magnifier Mount. AR height irons sights are visible through the window underneath the optic only with the 2.26" Aimpoint Acro Mount Mk2.