The listing, AMATEUR RADIO CARDS 1 has ended.
A QSL card or amateur radio card is a written confirmation between two amateur radio stations or a two-way radio communication.
They were sent through the mail like a postcard to acknowledge reception. The card included call sign, frequency, date, etc.
These cards are from New Hampshire, Mississippi, and Alaska in the 1949 and 50s. Original postage still on most.
There are 10 different cards.