Infanterie Sturmabzeichen (ISA) Infantry Assault Badge (IAB).
Altough it is not maker marked it can with certinty be attributed to maker Deumer.
On the right wingtip on the front is a small hole. The early ISA’s were fragile to make and easy to damage, which is why in later years they were made of massive metal.
In good condition and with the hole an interesting anomaly.