Telescopic Sighting System
The Telescopic Sighting System (TESS) was a sight used on the FV4201 Chieftain tank and RAF F-4 Phantom aircraft. == Usage == The TESS was trialed and introduced in the early 1980s originally as a tank sight for the FV4201 Chieftain.
Source: Wikipedia — Telescopic Sighting System (CC BY-SA 4.0)