Too small to be a photo pack (1.5" by 2.1" for the Powers card, Leons is slightly bigger).
I call these "Album Cards", similar to the many Cuban Issues of the 40's and also things like this...
1940 UO-Unc. Associated Stations (gasoline station) SF Seals (1.75" by 2.4")
These were collected then glued into an album provided by the gas station