The 3.7 cm KwK 36 L/45 (3.7 cm Kampfwagenkanone 36 L/45) was a German 3.7 cm cannon used primarily as the chief weapon of variants of the German medium tank the SdKfz.141 Panzerkampfwagen III. It was used in vehicles that saw action in the Second World War. It was essentially the 3.7 cm PaK 36 in use as a tank gun.