The SU-100 was developed in 1944 and was an improved SU-85 based on the same T34/85 chassis. After testing with different models of 100mm gun, the D-10S cannon was used. The hull armour was also increased from 45mm to 75mm. The SU-100 saw extensive service in the last year of WWII with 2,335 vehicles built by July 1945 and was capable of destroying any German tanks in service at that time.