The backs of these card vary; some feature an ad for Peck & Snyder Base Ball Player Supplies, the issuer; some have text giving information about the card then the issuer; some have other advertising, the space having been sold to other firms; some have a list of the players on the team.
This is widely recognized as one of the earliest true baseball cards, according to how one defines the term. The method of issuance is unknown, although they were probably given out at games or within the Peck & Snyder store as free advertising. Although cabinet cards and similar photographic cards existed at the time, this was a mass-produced item meant to be distributed to the public.
These exist in two forms; the small and large formats don't simply vary in size, but also employ different photos.