Germania, in days past you could sometimes find them on cover in a dealer's "cheapo" cover boxes, if you were really lucky.
Here is one I came upon a couple pf decades ago. It has a Chemnitz registration label with the Karl-Marx-Stadt (new name in DDR). Also, it is a turned cover, with the inside franked with a 4 pf. "buildings" stamp with Muenchen cancel.

