Bloke takes a look at the OG SUIT sight: Sight Unit, Infantry, Trilux. Most commonly seen mounted on an 7.62mm L1A1 SLR, this sight was available to infantry in the British Army from the mid-70's onwards, and is very forward thinking. However, the mount is hot garbage, which is probably why you don't see them so much in archive footage or photos.

The Israelis also adopted them, for use on 5.56mm M16 rifles.

Let's take a close look at the thing, shall we?