Studies have shown just how bad light is for your quality of sleep. When your brain senses pure darkness, it causes the production of melatonin, the chemical of sleep - that's where a sleep mask that blocks the light out will help you sleep better and deeper. It is made from soft cotton and at the back, it has a super soft elastic so it won't leave any marks on your hair and it will not pull or damage them. Every mask has an additional black layer of fabric inside. 9.05' x 3.93".