The best magic is the miracle that just happens with no apparent help from the magician other than saying, "Abracadabra!" That kind of miracle leaves the spectator declaring, I can't believe my eyes!

Such a miracle is Campbell's Cube-Off - the cleanest, utterly impossible penetration I have ever encountered with perfectly natural handling and not a false move anywhere. Repeat it again and again and still leave them baffled - magicians and laymen alike.
 
Imagine you have bought this marvel. Here is what happens: A spectator pushes a multi-coloured wooden block into a rectangular tube which is closed at one end. The block is solid, apart from a small diameter hole through which a wand can be passed.

Large round holes near the entrance of the tube allow the block to be seen clearly as it is inserted. The  tube is turned upside-down and the block drops to the closed end, where it is still clearly visible through two large holes in the sides of the tube.

The spectator passes a wand through the small hole in the block and holds each end of the wand. The highly visible block is clearly imprisoned.

The tube is then allowed to swing around the wand until it is upright with the open end at the bottom. Another spectator is invited to place her palm-up hand under the tube. The magician says the magic word, she gently taps the mouth of the tube with her open palm and the block drops visibly into her hand ready for examination. The original helper is left holding the wand, which he can also examine to his hearts content. The tube is removed from the wand and shown empty.  

By now their eyes, and every other pair in the audience, are as large and round as the holes that allowed them to watch every detail of an impossibility taking place... under their very noses.

This is the stuff of which real magic - and magical reputations! - are made. A hard trick to follow - but a breathtaking finish to any close-up or cabaret act. Very highly recommended.