The Reflex Sight appears as an attachment exclusive to Call of Duty 4: Modern Warfare's campaign, either mounted to the G36C or M4A1. It is nearly identical to the Red Dot Sight in terms of zoom and accuracy, but has a different appearance.
The Reflex Sight is a non-magnifying "electronic sight" that uses focusing optics to show a reticle floating out in front of the weapon. It depicted as a old style "tube" Red Dot Sight with the name "ArmPoint Mark ll Red Dot" on the side. It features a customizable reticle like other Red Dot Sights in the game. The Reflex Sight is available on most Assault Rifles, Submachine Guns, and Light Machine Guns, and can be considered the equivalent of the Holographic Sight from Call of Duty: Modern Warfare 2.
The differences between the Reflex and other Red Dot Sights are purely aesthetic. Compared to other Red Dot sights, the Reflex Sight has a slightly larger optical window, allowing for better vision around the reticle. However, the tubed casing for this early Red Dot Sight is rather bulky compared to simple open Red Dot Sights, and thus isn't as commonly used as its counterparts.
The Reflex Sight appears in Call of Duty: Black Ops II, and this time it replaces the Red Dot Sight from the previous games. On most weapons in 2025 it is identical to the Red Dot Sight in Call of Duty 4: Modern Warfare and Call of Duty: Modern Warfare 3. However, when equipped on handguns, the Reflex Sight appears smaller, similar in shape to the Call of Duty: Modern Warfare 2 Red Dot Sight. When applied to 1980s weapons in the campaign and Zombies, the Reflex Sight uses the Call of Duty: Black Ops Reflex Sight, with the exception of Soviet weapons, which takes on the appearance of their counterparts' Red Dot Sight instead (the same as the handguns from 2025).