ESP Cube - Aluminum Sliding Block

An elegant cube slides along a string and stops at the magician’s order... challenging the gravity law! Then it starts sliding again and, at another order, it stops again. Even spectators can try to give orders to the cube, but it will slide down without obeying them. The cube is made of a unique block of burnished aluminum. All can be given out for examination. The trick is simple, but undecipherable and can be done right in front of unaware spectators. The cube has 1.6” sides.