SUSAT

Not to be confused with the ACOG.

The Sight Unit Small Arms, Trilux, or SUSAT, is a 4x optical 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.

Use
SUSAT is the primary sighting system for the British Army's SA80 series weapons and L108 and L110 light machine guns. It is also used in the armies of Cameroon, Oman, Spain and Sweden, in assault rifles such as the Swedish Ak5-B and the Spanish CETME LV. A similar unit known as the Trilux SUIT sight was used on the L1A1 SLR

Recticle
The reticle of the SUSAT is of unusual design. Unlike the traditional crosshair layouts commonly used, which are in essence a cross intersecting the target, the SUSAT has a single obelisk-shaped post protruding from the bottom edge of the sight. This type of reticle is sometimes referred to as the "German Post". This obscures the target at long range and the foreground. The reticle is tritium-illuminated for low-light condition aiming. The radioactive tritium light source has to be replaced every 8–12 years, since it gradually loses its brightness due to radioactive decay.

Manufacturing
SUSAT is constructed from a one-piece, pressure die-cast, aluminium body, into which the eyepiece, objective lens and prisms are fitted as assemblies. The SUSAT sight was developed in Great Britain by Royal Armaments Research Development Establishment (RARDE) and is manufactured by United Scientific Instruments and Avimo, now known as Thales Optics

Specifications
SUSAT L9A1 Length: 145 mm Height: 55 mm Width: 60 mm Weight: 417 gram Magnification: 4x Entry eyepiece: 25,5 mm Exit eyepiece: 6,0 mm Field of vision: 10 degrees Eye distance: 25 mm Light permeability: >80% Illumination: Red tritium, glass ampoule Illumination strength: Adjustable Tritium ampoule lifetime: 8 - 12 years Focus: -0.75 to -1.25 dioptres Operational temperature: -46 to +71 °C