The Sturmhaubitze 42 was a variant of the Sturmgeschütz III Ausf. F or Ausf. G which replaced the 75 mm anti-tank gun with a 105 mm L/28 howitzer. The choice of gun options is provided in the Plastic Soldier StuG III kits although this is not explained in the kit instructions. My StuH 42 also carries Zimmerit anti-magnetic mine paste made from Mr. Surfacer 500.