[Optional Size: 6-inch(Outer dia.: 8-inch; inner dia.: 6-inch).9-inch(Outer dia.: 11-inch; inner dia.: 9-inch). Red bag is removable from hatch(the bag is not waterproof). Provide storage space to hold your belongings.Easy to lock and open the cap. Made of special plastic very durable.Foam gasket protects hull from damage. Durable lid with locking mechanism.Easy to install and remove stainless steel screws included.]