This easy to do effect requires absolutely no skill. Just pull on the string and the mechanical box does all the work for you. In effect, a small square panel with a small hole through it is removed from the box. The panel is totally examinable. A borrowed ring is tied on to a piece of string which is passed through the hole in the panel. The panel is reinserted back into the middle of the box and the end of the string is passed through the top of the box. Once the lid is back in place, the magician magically pulls the ring through the small hole in the panel, into the top section of the box. Again, the panel is removed and examined and the ring is returned to it's owner. How on earth did the ring squeeze through such a tiny hole?