Define
A small card people keep (pretty, useful, or collectible) that carries the brand after the encounter.
Mechanism
Retention object. The gift is the media. Recall is paid for by usefulness or delight, not by repetition.
Verdict
We can put a physical or digital keepable in someone's pocket and they will not throw it away.
Don't
The card is junk the day after. A flyer that is not kept is just a flyer.
Rights-cleared examples
A-Corn Salve 'knocks the toe corn' trade card
Acorn Stoves and Ranges trade card (front)
Advert for Lydia E. Pinkham's "Vegetable Compound" to be used for all female complaints, showing a young girl wearing a red hat
American Extra Soap trade card
An old trade card (George Inn, Southwark)
Arbuckle Bros. (3093003361)
B. T. Babbitt's Best Soap and 1776 Powder trade card
Bartlett's blacking, bluing and stove polish 'Afghan warriors' trade card
Burdock Blood Bitters trade card
C.I. Hood and Co. (2922694690)
C.I. Hood and Co. (Apothecaries) (3093650698)
C.I. Hood and Co. (Apothecaries) (3093747676)