I recently came across this service medal being offered for sale on
ebay and it struck me as unique (in the seller's terms "rare") as it was apparently issued in appreciation to Boston Postal Service men who were veterans of World War I.
As I had never seen it before, I thought I'd share it here. Note that the inscription on the reverse suggests that it was issued by the "Boston Postal Clerks Mutual Benefit Association":
http://www.ebay.com/itm/Rare-WWI-Se...em3ce703d0cf