The 10 cm Nebelwerfer 40 (10 cm NbW 40) was a heavy mortar used by Germany during the Second World War. Much like the American M2 4.2 inch mortar it was intended to deliver chemical munitions, such as gas and smoke shells, as well as ordinary high-explosive shells. It was derived from Rheinmetall's Nebelwerfer 51 and 52 prototypes of the late Thirties which were attempts to develop a more accurate and longer-ranged mortar than the 10 cm Nebelwerfer 35. The NbW 40 is one of the better examples of German over-engineering since it fired a slightly heavier bomb over twice as far as the NbW 35, but weighed almost eight times more than the earlier model.