This baton-shaped thing is actually a lifebuoy. Compared with the lifebuoys we usually see, it's much smaller in size. If you see someone drowning in the water, you can accurately throw this portable lifebuoy to the location of the drowning person. Once this portable lifebuoy touches the water, it quickly spreads into a horseshoe-shaped float, thus becoming a life-saving device. That's because this portable lifebuoy contains chemicals that begin to expand upon contact with water. Therefore, it naturally expands from the size of a baton into a lifebuoy.