This bottle cap is prepared and placed in the bottle in advance. Make a small opening on the label of the bottle, then put a cap that is the same as the original cap of the bottle with an iron piece and put it into the bottle, and then Seal the label as it is, put on a magnetic ring, and attach the bottle cap inside to the label so that the cap is not visible from the outside. During the performance, take a normal bottle cap and slap it on the bottom of the bottle. At this time, let go of the hand with the ring, so that the inner cap will fall off, and the outer cap will be hidden using techniques. It will look like the bottle cap is worn through. Over the bottle.