This 3D model was originally created with Sketchup 13 and then converted to all other 3D formats. Native format is .skp 3dsmax scene is 3ds Max 2016 version, rendered with Vray 3.00 Sometimes known as the Bison. The larger Ausf B chassis made possible the mounting of heavier guns with removal of the turret. The largest was the 150 mm heavy infantry gun, the sIG 33. This mammoth piece was relatively short and fit just barely in a tall superstructure not only built up to the vehicle's 2.8 m height but also out over the tracks to their full 2.06 m width. The superstructure armor was light at only 13 mm and only protected the front and sides. The heavy resulting weight of 8.5 tons overstressed the chassis and ultimately, the vehicle was not a great success. 38 were converted from Ausf B tanks in February 1940 and they served with six heavy SP infantry gun companies with survivors in service into 1943. The sIG mounting was capable of 25 ° of traverse and 75 ° of elevation, and could be depressed to -4 °. It used a Rblf36 sight, and ammunition was carried separately, there being no room for onboard shell storage. The sIG would be mounted more successfully on larger chassis as the war progressed.