Contains: Grade 1240 quality natural corallite coconut shell, activated carbon. Purpose: Increases TDS (total dissolved solids) and enhances alkaline pH levels – (Installs on the ‘water in (source) hose’). Also supplies trace elements beneficial to human health. Rated Lifespan: 1,000 gallons or approx. 4-6 months. This filter is optional and would install in the Water Storage Tank.