Manufacturer of the SUIT (Sight Unit Infantry Trilux) sight. This was an early 1970s attempt at providing the infantryman with robust optics for use in both an urban and battlefield environment, though it found its niche on the streets Ulster where it was a useful tool - enabling quicker acquisition of fleeting targets than iron sights.
On the other hand, the sight was clamped to the SLR top cover by a spring, which - with age and wear - would weaken, leaving the sight prone to move around with recoil, rendering the waepon significantly less accurate than if fired using iron sights.
The SUIT sight is generally regarded as the predecessor of the SUSAT. Mainly used on the L1A1 self-loading rifles (SLR), the sight could (allegedly) also be fitted to other unit weapons, though quite why is a mystery.