Hispano 20 mm cannon sprung feeder drums Hispano 20 mm cannon sprung feeder drums
Fitted to later Spitfires and most aircraft with the Hispano cannon from then on. This is not a drum containing ammunition, but a clockwork wound device that feeds the ammo belts into the gun when fired. This avoided the very large cannon magazines seen on early Spitfires for example.

11 Right hand
4 Left hand