The schmaltrum turret could be found on what tanks other than the Panzerkampfwagen IV?
Schmalturm The Schmalturm turret was a tank turret designed for use on the Panzer V Ausf. B Panther II medium tank, Panther A and G medium tank, Panzer IV Ausf. J medium tank and the VK 30.02 DB (a medium tank prototype). The turret's shape resembled the Soviet T-34 tank turret. It featured a narrow front to maximize protection while minimizing weight. It was both lighter and easier-to-manufacture than the standard Panther turret. The turret had a stereoscopic rangefinder with lenses on either side of the turret, located in spherical bulges. No Schmalturms entered series production.
10 cm schwere Kanone 18 The 10.5 cm schwere Kanone 18 (10.5 cm sK 18) was a field gun used by Germany in World War II. The German army wanted a new 10.5 cm gun as well as 15 cm howitzer which were to share the same carriage. Guns are heavier than howitzers due to the longer barrel. This also led to the 15 cm sFH 18. As such both weapons had a similar weight and could be carried by a similar carriage. By 1926 Krupp and Rheinmetall had specimen designs, and prototypes were ready by 1930, but was not fielded until 1933–34. Both Krupp and Rheinmetall competed for the development contract, but the Wehrmacht compromised and selected Krupp's carriage to be mated with Rheinmetall's gun.