SUSAT

SUSAT, short for Sight Unit Small Arms Trilux, is a 4× optical rifle sight that was developed for the British SA80 family of assault rifles. It combines daytime magnification with integrated illumination to provide a single everyday aiming solution for both day and night conditions. The trilux designation refers to multiple illumination elements built into the sight to aid visibility of the reticle across lighting environments.

Design and features

The SUSAT is mounted on the rifle’s upper receiver and is designed to be rugged, weather-sealed, and adjustable for windage and elevation to allow zeroing at standard engagement distances. It uses fixed 4× magnification to balance target identification with aiming speed. The reticle is illuminated through a combination of tritium-based illumination for continuous visibility in darkness and a fiber-optic/daylight illumination channel for daytime use. In addition, an infrared (IR) illumination option is provided to enable targeting with compatible night vision devices, allowing soldiers to aim in low-light conditions without visible light signatures.

Operational history

Introduced for the SA80 family in the late 20th century, SUSAT served as the standard optical sight on the L85/L85A variants and related configurations used by the British Armed Forces. Its integrated day/night capability was intended to improve first-shot hit probability across a range of operating environments. The sight saw extensive operational use and was retained through successive updates of the rifle platform, remaining familiar to many operators for decades.

Variants and legacy

Over time, SUSAT-based configurations were complemented or superseded by newer aiming solutions in some roles, as part of broader upgrades to the SA80 platform. Nevertheless, SUSAT remains a notable example of a dedicated, purpose-built battlefield optical sight designed for a modular, modern-service rifle.