A ring-shaped device used as a flotation aid. There are two types, which may be distinguished based on their design and the context in which they appear:
Innertube - Air-filled and intended for recreational use. Comes in various colors; also sometimes translucent.
Lifebuoy - Made of a durable foam and intended for saving people from drowning. Usually orange or red-and-white striped, without seams, and sometimes with a rope.
