Andrew and Val: they are strip cards from a horizontally-oriented set of ten cards that use the artwork from a 1925 4 on 1 Exhibit set. Very, very rare; not all ten of the assumed cards have come up for sale over the 20+ years I've been looking. I have never seen a full strip. Here is an analogous boxing strip:
Cobb:
Simmons:
Here are some 4 on 1s using the same artwork:
Anticipating the next question, I know they aren't cut down 4 on 1 cards because the stock is completely different. Thinner and with both sides having polished white paper.