SUSATs, or Sight Unit Small Arms Trilux, is a tritium illuminated small arms sight with a 4x optical zoom. Amongst others, it is attached to the SA-80 family of weapons in place of the iron sights, however is being phased out in the British Army in favour of ACOG (Advanced Combat Optical Gun) sights.
Sitting around 15cm long and 6cm wide, the aiming point is a German (or obelisk shaped) reticle which can be made to glow through the presence of tritium. Underneath the eye piece is a dial to change the range, and above are post and hole iron sights in case the main SUSAT unit is rendered inoperable in combat.
Actions on breakage
Due to the radioactive contents of the sight unit, the official policy on breakage is to evacuate the room or area and open windows to allow a flow of air through the space as theoretically exposure can cause infertility. In reality such an event is met by much swearing, and in combat the luxury of evacuating the area immediately surrounding the broken unit cannot be afforded.