a "waffle". It is used to cover a player's 2nd hand in some table games. Those are Pai Gow, Asian Poker, and 1 or 2 others. It prevents players who play 2 hands from sorting their hands at the same time, and "accidently" mixing cards to get a better hand. One hand is sorted, the waffle is placed over their cards, and the player proceeds to sort their 2nd hand. Does that make sense?
Anyway, they are translucent, and about 3" by 6".
I can't believe somebody snagged one already!!!! Crafty buggers! Anything that's not nailed down is fair game to collector's, I suppose!