Back when radio stations used to play music that was pressed on vinyl records, not CDs or from a giant hard drive, the disc jockeys would put the needle in the groove and send the hip sounds out across the airwaves.
In 1989 Topps decided to do the same thing. Sort of. This looks like a regular issue 1989 Topps card. Until you realize that the card measures 3-1/4" x 5-1/4".
If you inserted the card into the Sportstalk player you would hear information about the baseball player on the card. Narrators on the 163 card set were Don Drysdale, Joe Torre and Mel Allen.
Wikipedia has a good summary and complete checklist and WFMU has a nice explanation and good photos of the player and cards.
So sit back and and listen to old ballplayers talk about other ballplayers in high fidelity. Or not.
Or settle in and listen to five classic baseball games as they were heard on the radio (1954-1964). My thanks to MLB and Archive.org for making these (and other) games available.