The concept of the StuIG33 was to mount a high-calibre, high-explosive weapon on a fully enclosed superstructure, the gun chosen was the potent 150mm SIG-33 heavy infantry gun on a Pz Kpfw III chassis. The strength of the �Heavy escort artillery� as an assault vehicle in armoured units proved to be a success. The first vehicles were issued to Sturmgeschutz Abteilung 177, with orders to employ them in Stalingrad. Includes 2 vehicles.