We have an  Advertisement Post Card Vintage item.  It measures about 5 5/8" x 3 1/4".    It was put out by H D Huggan Drug co in Boston Ma.  It bosts that Vitamin C was available at reasonable prices.......  There is a preprinted 1 cent stamp on the front.  These (on initial posting I have a few) have not been sent/addressed, they are nos.