This Erkennungsmarke (EKM) from Flak-Scheinwerfer Ersatz Abteilung 15 is a rare artifact tied to the Luftwaffe's specialized searchlight operations during World War II. It represents a crucial aspect of Germany’s nighttime air defense system.  
Unit Overview:  
- Flak-Scheinwerfer Ersatz Abteilung 15:  
This replacement unit trained and supplied personnel for Flak-Scheinwerfer units, which operated searchlights to locate and track enemy aircraft during nighttime air raids.  
The 15th Ersatz Abteilung was responsible for ensuring a steady flow of trained reinforcements to active Flak-Scheinwerfer Abteilungen in high-priority areas.  
- Ersatz (Replacement) Role:  
Ersatz units did not engage in combat themselves but served as training and reserve pools, preparing soldiers for deployment to active searchlight units at the front or in air defense zones.