armband

中文： 队长臂章、游泳臂圈、臂章

1. A band worn around the arm, usually to symbolize mourning or protest.
2. A band worn around the arm of the captain of a team.
3. One of a pair of inflatable plastic bands, normally worn on the upper arms, to help the wearer (often a child) float in water and learn to swim.

复数 armbands