The Cordura Sandbag - Empty, Black - Holds 15 lb is a useful product by Mathews. It is available different veriety and shapes and weight in market. It is used for the safety and securing the bases of light stands and set walls. Most are cordura nylon, some are vinyl covered and waterproof.Some models of sandbags are shipped empty, for convenience and economy. They can be filled with sand, or any type of weight you provide, and emptied for storage, or transport.