This effect was first put out by Vincenzo Di Fatta in 1997.   The originals were made with bridge size cards, but DiFatta has recently re-released the effect, with poker size cards and Bicycle Rider backs.  (note:  the cards are not on Bicycle stock, and in fact they are slightly wider than standard poker size cards.  More on that later...)

The magic of science at work.  These special cards have some sort of cool heat sensitivity, so the pips disappear when you hold the card near a flame or even hot light bulb.    Show a prediction card facedown.  Have a card selected using your favorite force.   The prediction doesn't match!  It's a nine of diamonds  and the selection was the five of diamonds.  Well, magi just waves his magic Bic lighter flame under the card, and four of the pips VISIBLY vanish.  Leave the card away from heat for a while, and the pips come back.     (The pips return automatically after about one minute)

As mentioned above, the cards are printed on what appear to be Poker sized cards, but they are just a bit larger.  If you put one of these cards in your standard poker deck, it will stick out a minute amount.   I find this "bug" to actually be a "feature" (as the software people used to say) -- it makes it easy to cut the deck to an apparently random prediction card, with no sleight of hand.  So I kinda like that the cards are a bit wide.

If using a candle, match or lighter as your heat source, be careful -- don't burn yourself, and know that you can scorch the card if you get too close.   But you do not need to be very close to the card for the visual transformation to occur.

You get TWO different changing cards -- I have a set with 7C and 9D, and a set with 5H and 9S.    You can message me to let me know which set you prefer.   If you do not message me to let me know, I will send whichever one I grab out of the box.  If you buy two sets, I will send you two different sets -- four different changing cards.  

These di Fatta sets work very well, and should hold up over time (unless you get too close with the flame!)   There have been some similar (cheaper) sets from other manufacturers that do not work or look as good.  Buyer beware if you find this neat item for less!