Impossible Penetration

New, improved design. Solid brass, practicable size for parlours and close up, smooth function. Three things everyone knows: a screw, a nut and a ball chain, such as those used to fasten drain plugs. The screw and nut have a small special feature. They are each drilled through in the middle. You are about to show the audience why: If you turn the nut onto the screw so that the holes of the nut and screw are congruent, you can guide the ball chain through the nut and screw. The nut is thus clearly secured against twisting or loosening. Nevertheless, you can immediately turn the nut from the bolt without a cover or secret fumbling. If you then hold the nut directly in front of the spectators' nose, you can clearly see that the chain runs exactly through the middle of the nut. Immediately let the nut slip off the chain into the hand of a spectator who must confirm that it is a commercial bolt, an unprepared nut and an untricked ball chain.