These cards are called sample cards. They were mailed out to prospective customers in the hopes they would order large amounts to sell in their shops. They could have also been passed out directly by salesmen as they went on their routes.
KRAEMER ART CO.

Birthday Cards
#30
Birthday Cards
#410

Birthday Cards
#500
Special Floral Cards #1

Special Floral Cards
#3
Flower Cards #400

Special Floral Cards
#4
Scenery Cards #219

Special Easter Cards
#88-A
Special Christmas & New Year Cards #A
W. H. STANAGE & CO.
U. S. NOVELTY CO.
NATIONAL COLORTYPE CO.
The card on the right above is a reply from the National Colortype Co. for an order that had been placed with them.
THE NEWPORT STUDIO

134 West Fourth St., Cincinnati
This pane of stamps was removed from a much larger pane. These stamps were, I believe, used by the postcard salesmen as an easy way to show a prospective customer their current line of cards. They could also have been stuck on the salesman's order form as a way to ensure that the customer received the correct cards. I have seen a complete sheet of stamps for Kraemer, unfortunately it was much too expensive for me at that time.