Card fronts show a black-and-white photo, surrounded by a red border, with the player's last name and home city at the bottom.
Card backs contain simply an ad for Old Mill cigarettes with the set title (Base Ball Subjects), but the top line gives the series number.
This was a minor league release by Old Mill Cigarettes - literally; each of the 8 series of cards were devoted to a different city's minor league teams. Thank goodness for collectors that the card backs clearly differentiate the series number, or else sorting all of these would have been a nightmare.
Some series are more scarce than others.
Since these were minor league players, very few of them are widely known to modern collectors, so most cards in the various cities are considered 'commons.'
The only two really notable cards in this set are [Casey] Stengel in Series 6, Blue Grass League; and [Shoeless Joe] Jackson in Series 8, Southern Association.