The original Jagdpanzer IV tank destroyer was based upon the Panzer IV vehicle and used extensive sloped armor with the 48-caliber 7.5cm gun that had already proven its worth on other vehicles. In January 1944, it was decided to upgrade the Jagdpanzer IV, with the powerful 70-caliber 7.5cm anti-tank gun installed in place of the original 48-caliber weapon.