Some modern naval uniforms continue to use bell-bottomed trousers as a potential life-saving device. The trouser material is made of cotton fibers that swell when wet and can hold air. In the event of a sailor falling overboard or having to abandon ship without a life vest, the bell-bottomed trousers can be quickly removed in the water without having to remove footwear. As part of their survival training, sailors are taught to remove the trousers while floating, tie the leg bottoms in a knot, and then use one of several methods to inflate the trousers with air. The inflated trousers can provide extra flotation while awaiting rescue.