mm Eye relief: 25 mm Light permeability: >80% Reticle 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 Range Settings: 100 to 600 meters (SUSAT L9A1) or 300 to 800 meters (SUSAT L12A1) in 100 m intervals NATO Stock Number (NSN): 1240-99-967-0947 (Sight Unit Small Arms Trilux (SUSAT) L12A1) See also C79 optical sight ACOG Optical Sight L2A2 SUIT Sight External links United Scientific Instruments—Official website SIGHT UNIT SMALL ARMS TRILUX (SUSAT) Firearm sights British Army equipment Military equipment introduced in the 1980s