In September of 1939, Krupp received a design proposal from for a  purpose-built self-propelled howitzer. Unlike earlier motorized  artillery, this was not an adapted or converted vehicle, but rather  expressly designed for this role. A 10.5cm le.F.H.18/1 was mounted in an open-topped turret. The light field howitzer could be rotated in this  turret through a 70-degree arc. The sides of the turret were tapered  downward toward the rear, allowing excellent side visibility. The new  vehicle, initially known as Pz.Sfl.IV b, was later designated  Geschützwagen IV b für 10.5cm le.F.H. 18/1(Sf) (Sd.Kfz 165/1). Two  vehicles were ordered for testing, which were delivered in January 1942. Even before that, during Fall 1941, a series of 10 of the new vehicles  were ordered for troop trials.