The best selling water bottle purifier. EPA registered to remove all types of microorganisms, including viruses. Lightweight, simple design fits into standard water bottle and cup holders. Purification method: Virustat technology plus microfiltration and carbon. Bottle capacity: 26 oz. Cartridge capacity: Up to 26 gal. Weight: 7 oz. Height: 11". Virustat kit is the complete filter element. Cyst filter is only the first stage of the Virustat filter. Replace Cyst filter when flow is restricted.