Use the same material as outdoor waterproof dive bags - 500D double-sided PVC Waterproof Material, stronger and more waterproof than ordinary 600D polyester or Oxford cloth bags. Not only that, made of thick PVC net clamping cloth to ensure it is airtight, watertight, and durable. Comes with a small inner pocket and a detachable shoulder strap. This bike pannier can use as a shoulder bag or laptop bag while not cycling.