This is the Sulfa Shaker Outer Envelope. The small sterile, sulfa shaker was included inside envelope. These envelopes were supplied twelve (12) units to a box. The box of shakers was utilized in aid stations. It would be likely that these found their way into the hands of field, combat medics.
I have attached a construction sheet (with one repro envelope, picture of original and instructions) as well as an envelope only sheet.
EDIT: Scaling Fixed! Attachments are corrected and ready for download! Enjoy!