Because SD 2s were always dropped in groups (never individually) the discovery of one unexploded SD 2 was a reliable indication that others had been dropped nearby. This bomb type was one of the first cluster bombs ever used in combat and it proved to be a highly effective weapon. The bomb containers that carried the SD 2 bomblets and released them in the air were nicknamed the "Devil's Eggs" by Luftwaffe air and ground crew.[2]