Kennard invented it and we make it. A solid block of walnut with a long bolt running through it is displayed. The bolt is removed and handed to a volunteer. (It's store bought and can be found at any hardware store.) The bolt is replaced through the walnut block and a nut is spun on snugly. Any coin from a dime, quarter or even the new dollar coin is borrowed then visibly penetrates through the bolt. The nut is spun off the bolt. The bolt is removed and immediately handed to the volunteer along with the nut and walnut block. The Block and Bolt trick defies detection as to how it is done. Note: The bolt does not unscrew in the middle. No magnets. Only one coin is used. Good directions. Easy to do. A real fooler. Foreign and domestic coins can be used. Made from select walnut.