Specimens of United States military payment certificates are enigmas to the hobby. A few pieces and sets are known in collections. Specimen certificates were prepared in two ways. 

  The first method , used for earlier series, was to perforate the word specimen into replacement certificates. The second method , used for later series, was to print the notes serial number with all eight zeros. A third type of specimen has also been observed. It was made simply by stamping the word specimen on any available certificate.

  A few examples are shown below.