The magician shows an hexagonal steel piece with a hole just broad enough to let a ball pass through. He introduces the bolt and screw the nut. He places the ball in the higher aperture. It looks impossible that the ball pass through. Meanwhile, it happends ! The ball pass slowly through the bolt.
Very easy to do, with this amazing device !
Very good manufacture.
Delivered with all necessary stuff & a storing case (as on the picture).