Where to buy invisible ink

Everyone knows that China marked cards factory have marked playing cards for sale! But a few people know the invisible ink marker pen which actually it is one kind of invisible ink for playing cards. We can use them to mark poker cards, and it is one of the best way to mark cards by hand.
We have invisible ink for sale. Please note that our invisible ink and glasses to read the ink, not invisible ink pen for kids. After your marking playing cards marked all 4 corners, you can use infrared contacts or glasses to read invisible ink marked deck of cards.
If you want more details about how to mark cards while playing poker, please contact GS marked cards suppliers.