This is a WA arm-badge, also called a Bevo woven armbadge. It is originally attached to a piece of black cut-out cloth from what appears to be blackshirt!
The size of the cloth is approximately 14 x 10 centimeters.
These were worn by the WA, the uniformed blackshirts of the NSB (Weerafdeling), the dutch equivalent of the German SA (Sturmmabteilung).
Hard to find like this!