Also, the EOTech holographic sight has been seen in use. The most common optics would be the SOPMOD Trijicon ACOG reflex and day optical scope, and the AimPoint M68 red dot sight. Depending on what unit they are going to will determine their optics as well as availability. Optics is not standard for the Mk18 Mod 0.A4 - Of or referring to a characteristic of the M16A4 (for example, a flat-top A4 upper receiver) ABC - Armalite, Bushmaster and Colt (considered by many to be the top three manufacturers of AR-15) ABCR - Armalite, Bushmaster, Colt and Rock River Arms (a variant of ABC used by those who also consider Rock River Arms to be a top-tier.
