ABC Block - Harries Magic from The Magic Authority. The Magic Experts...

You show three blocks with the letters A B C on them and a hat or a paper bag absolutely empty. The blocks are threaded on the stand in alphabetical order. They are covered with an elegant tube for a moment. After some byplay the tube is removed and one of the blocks has vanished. When the magician or even an assistant from the audience, looks in the hat (or paper bag) the block has returned to the hat! The blocks are 7x7cm and the tube is 22 cm high.