The Gooper Hermetic Pocket is waterproof, air, gas, sand, and dust proof up to 100 Ft. deep. The technology is based on simple science. When you place two Gooper Hermetic magnetic strips next to each other and let go, they (click) smack together to create an instant waterproof seal. It's as easy as open, insert, and just let go. Automatically closing when you let go and 100% waterproof. The pockets are made of biodegradable black "non-stick" Thermoplastic polyurethane (TPU). We use 90% recycled fabrics.