The SU-85 was a Soviet self-propelled gun used during World War II, based on the chassis of the T-34 medium tank. Earlier Soviet self-propelled guns were meant to serve as either assault guns, such as the SU-122, or as mobile anti-tank weapons; the SU-85 fell into the latter category. The designation SU-85 is derived as follows: 'SU' stands for the - self-propelled carriage, while "85" signifies the bore of the vehicle's armament, the 85 mm D-5T gun.