SUSAT（英语：Sight Unit Small Arms, Trilux，意为：由Trilux生产的轻武器瞄准设备）是一种4倍的放大倍率的快拆式（英文：Quick-detachable）瞄准镜，在黄昏和黎明时段，可以使用内置的氚管作供电照明。此瞄准镜在现在的**之中的全称为SUSAT L9A1。此瞄准镜的设计并不是作为狙击手专用的瞄准具，而是要安装在各种步枪上，而英**队亦期望被所有的步兵使用。类似这种瞄准镜的是美国Trijicon公司的ACOG光学瞄准镜和加拿大ELCAN公司的C79光学瞄准镜。

The Sight Unit Small Arms, Trilux, or SUSAT, is a 4× telescopic sight with tritium-powered illumination, utilised at dusk or dawn. The full name of the current model is the SUSAT L9A1. The sight is not designed as a sniper sight, but is rather intended to be mounted on a variety of rifles and to be used by all infantrymen. A similar device is the Advanced Combat Optical Gunsight.