The gunner and commander in a tank T-90S have been provided with night vision device ESSA based on principal of thermal imaging which can be used to search, detect and identify targets by day and night under normal and adverse conditions and engage them effectively using main gun and coaxial MG. The sight can be used to detect and identify targets having temperature difference of upto 2°C and engage them upto 4000 m using unguided and guided projectiles and coaxial MG. The mirror of the system being stabilised both in azimuth and elevation and being integrated with the FCS of the tank, a high deg. of accuracy and consistency is obtained using the sight while engaging both static and moving targets.