The Performer shows 5 cards face up in a fan.
Every alternative card is now turned face down, so the cards in the fan alternate face up and face down. The fan is closed and the cards passed through the performer’s hand. When the packet of cards is fanned again, all the cards are found to be face up again. The effect can be repeated as often as you like.
A very inexpensive card trick you can carry around in your pocket.