Contoured design allows complete freedom of movement to open and shut the eyes, while keeping the wearer comfortably inside a curtain of darkness. Scientific studies show that rapid eye movement or REM sleep is the most crucial part of the sleep cycle.Great for air travel, daytime sleep. etc.Washable/Reusable. Made of silky smooth bra-like material. So light you'll hardly know you're wearing it. Velcro fastener accommodates heads of all sizes. Contour design helps prevent smudging of eye make-up.