O'Keefe Party Coasters
They were likely a novelty giveaway at trade fairs & conferences
like the Carling & O'Keefe aluminum coaster sets.
My guess would be late Ontario 40's to 50s when brewery swag
was strictly controlled by the Ontario government. Info from Gordon Holder.
Coasters submitted by Don Kurtz, all 2 sided with various sizes and different
colors (of the same coaster)