There are two videos that come with this routine

The performer suspects the spectator's card is in one of them

then this book is UNRESERVEDLY RECOMMENDED

Evolution of our Magic - Charles Bach

Cheetah | Berman Dabat and Michel Ernest There are two videos thatA card index fast, slim and lethal Just like a cheetah Imagine if you could find any card, secretly, in one second. Now, with Cheetah, you can. A card index so thin that fits into ANY POCKET. It's very easy to learn, you don't need to perform weird moves, riffling, or mental calculations. The revolutionary design allows you to produce as many cards as you want, any poker hand and instant access to any four of a kind. This is THE card index for