This one-size-fits-all bottle stopper is made of seamless silicon rubber. The top view resembles a round hat with a crown and circular brim. The crown is formed by an upper layer of thick silicon rubber and a lower layer of thin silicon rubber. Between the crown’s lower layer and the circular brim is a protruding ring. Simply align the stopper on top of the bottle, then push down the outer part of the circular brim until the protruding ring grabs the mouth of the bottle. Release the circular brim and the circular brim adheres to the bottleneck to further seal the bottle. The O-shaped ring can be hung around the bottleneck to prevent losing the stopper. This design is non-toxic and has no sharp edges so cannot hurt the user if used carelessly, and can be wiped clean.