100% Mulberry silk on both sides, and 100% silk filling not cotton filling. Natural Mulberry Silk–Our 8.5″x4″ silk eye mask is made of top quality 19mm natural mulberry silk. It not only feel smooth against your skin but are also hypoallergenic, great for those with sensitive skin. Elastic Strap–0.4 inches width elastic head strap design. The headband design won’t tangle hair like contoured masks, fit for side-sleepers as well. Benefit–Lightweight and breathable.