The C79 Optical sight is a small arms telescopic sight. It is 3.4×28, meaning 3.4x magnification, and a 28mm diameter objective lens. A tritium illuminated reticle provides for normal and low-light conditions sighting.
"A 4x magnification scope for medium range engagements that can switch to secondary 1x iron sights."
— In-game description
The 4x-1x C79 is a optical sight featured in Insurgency: Sandstorm.