Premium Material: The scuba tank boot and cap are made of pp materials, which is able to support long service life. Diameter: 15.7cm/6.18inch. Design: The diving accessories has dense groove design in the inner side to prevent tank fall off. Use: The flat bottom protector is able to protect the base of your cylinders and assist in extending the life of expensive air tanks. Efficient Drainage: The tank features drainage channel hole that allow water to quickly, making it an ideal choice for underwater activities. Upright Storage Protective: The tank upright storage protective cover parts can ensure upright storage and protection of standing air cylinders. Specification: Material: PP Size Chart: Diameter: 15.7cm/6.18inch Package Includes: 1 Scuba Tank Cap 1 Scuba Tank Boot Note: Please allow slightly errors 1-2cm differences due to manual measurement.