This is a precision-made card pegger also known as a card punch that is based on the Dr. X design. A card punch is used to mark cards by adding invisible blisters to them (like braille) so you can find the cards you marked by feel.
These peggers were made by Nick Diffatte, who is the exclusive heir to the Dr. X line of gambling products and gimmicks and was taught how to make the various items that were produced under that brand.
These tiny peggers are secret weapons used by card cheaters to mark cards during play by attaching them to their fingers or thumb and putting in the work while handling the cards.
These types of punches have also been known to be secretly attached to tables, rings, watches, buttons, and other objects that might get in contact with cards.
The advantage of these types of punches is that they do not have to be adjusted like the pin versions and they will not pierce the cards since they do not have any sharp edges.
These peggers are tiny, so we are selling them as a set of two, so you have a spare, in case you lose one. They are made of brass and are around an eighth of an inch in diameter. No instructions.