This is a case with snap-on lid for a single deck of standard size playing cards.
It is the same design as my other two deck model, just reduced in height for single deck: Playing Card Holder for 2 Stacked Decks
I have a remix for smaller sized cards (56 x 87 mm): https://www.printables.com/model/762940-bridge-playing-card-holder
The author remixed this model.
Reduced size to fit a single deck of cards.