This is a pair of Luftwaffe Flak  Artillery collar tabs for a non-commissioned officer, Technical Sargeant, Feldwebel.  Bright red felt with silver dress and 3 eagles in the centre. 

Flak Corps (Flakkorps) was a massed formation of anti-aircraft (AA) artillery used by the Luftwaffe for anti-aircraft, anti-tank, and fire support operations in WW2.  

The Korps was made up of a number of AA regiements, brigades and divisions mostly intended to support ground units with concentrated anti-aircraft fire.  Sometimes also providing anti-tank support.  

Flak corps did not exist before World War II. During WW2 a total of six flak corps were organized by the Germans.  Numbering from one to six, in Roman numerals (I, II, III, IV, V, VI),   plus one short-lived special flak corps.