Youthwaters Stage 2! Portable Hydrogen - Alkaline Thermos - Water Filter Replacement Cartridge Only. Converts Regular Water Into Alkaline Ionized Microcluster Water + Healthy Minerals. The Life Span for This Filter Is Aprox 1-2 Months. Universal Works in Most Alkaline Thermos.for Best Results Replace Every 30 Days !!!!!!!!! + a Free Power of Nature Energy Negitive Ion- Anti Rad- Energy Card