An Erprobungskommando (EKdo) ("Testing-command") was a variety of Luftwaffe special-purpose unit tasked with the testing of new aircraft and weaponry under operational conditions. Similarly-named Erprobungs-prefixed squadron (staffel) and group (gruppe) sized units also existed at various times in the Luftwaffe during 1939-1944 to service-test new designs, usually numbered with the RLM aircraft designation system airframe number matching the aircraft they were meant to test, with the three digit number following the "8-xxx" RLM airframe number designating the unit, as with Erprobungsstaffel 177 (contracted to E-Staffel 177), charged with testing the A-0 production prototypes of the Heinkel He 177A heavy bomber.[1] The similarly-prefixed Erprobungsgruppe 210 was meant to have service-tested the Messerschmitt Me 210 twin-engined "destroyer" and light bomber, but that design's early aerodynamic problems caused the unit's transformation and expansion into SKG 210, a dedicated "fast bomber" unit using Bf 110s instead.