What a startling effect!
Let your spectator secretely select a card, and then you shuffle it back in the deck. You blow up an ordinary party balloon, place it in the balloon holder and press down on it. Pop! The balloon bursts, and the selected card is now in the balloon holder! Wow!
To make the effect even MORE spectacular, use these special transparent balloons. Your audience can see right through this clear balloon when it is in the holder, making it even more of a surprise when the card appears!