This is one great trick and only one of many possibilities. The magician hands out a pack of cards for shuffling and a group of envelopes. Envelopes and cards are passed to members of the audience. Each audience members chooses a card and places it in their envelope. The envelopes are then dropped one at a time into a bag for collection or onto a table.
The magician with his mind reading ability (and a little help) is able to tell each person’s card even though he has not touched the card or handles them in any way.
In the American version the reader is built into a rubber stamp which forces you to have each person rubber stamp the envelope which in y opinion is very time consuming The reader in the Japanese version is portable allowing you to place it in any number of places as suggested by Cesaral. Retails for $900 and worth every penny.