The Raupenschlepper Ost or 'Crawling Tractor, East' was a fully tracked truck used as both a prime mover for smaller AT guns such as the PAK40 and as a tractor in it's own right for delivering supplies. It's name was more commonly abbreviated to RSO and it was designed in response to the poor performance of wheeled vehicles in the mud and snow of the Eastern front. The RSO/01 had a pressed steel cab and truck like configuration. This particular variant was fitted with a special flotation kit.