WaterCubeTM is a unique 2-part container that is specially designed for emergency drinking water storage. WaterCubeTM has a separate, rugged outer shell to protect it for physical damage and ultraviolet light. The outer shell also provides the unique "stackable" shape, and has a retractable carrying handle. The WaterCubeTM inner container is a flexible heavy-gauge polyethylene bottle made of FDA approved materials. Drinkable water even after 5 years! (when using pictured Water Preserver Concentrate)