ESP Boxes by Astor

The magician asks the spectator to choose one of five boxes in a bag. The spectator opens his chosen box and puts something inside (for example a folded banknote). The spectator puts the chosen box back into the bag and mixes it with the other boxes. The magician digs into the bag and pulls out the chosen box. The boxes and the bag can be examined in the end. The trick does not require sleight of hand.