T80 is a further development of the T64. It was first produced in 1983. It is equipped with a 125 mm main gun and possesses many of the same complicated systems which the original T64 had, but free from problems. T80 has much thicker turret armour and the hull is protected by composite active armour. ABC-protection is standard and diving ability to 5 m depth. It is estimated that over 20,000 units were in operation by 1997 in Russia and the number was growing as its successor to be, T90, still was in a low level of production. This model was the first main battle tank in the USSR to use a gas-turbine engine.