If a German citizen was to go to war or to work under the IIIrd Reich, a Receipt card of Disability Insurance (Quittungskarte der Invalidenversicherung) was issued. After an important wound in the front that will also be issued to the soldier. Nice for display with you wounded badge ! 
Prices on the document are in ReichMark and years 194... !
Those documents in mint condition are rare to find as a lot of papers were burn or throw at the end and after the war. 
Price per piece