Filter Sorb F-400 Activated Carbon radon mitigation system is specifically designed for the removal of lower concentrates of radon gas in water (under 10,000 pCi/L). The system includes: (2) 13" x 54" mineral tanks (2) Gravel Sleeves for the tank beds (2.5) 2 Cubic Ft of F400 carbon (total of 5 Cu. ft) (2) Clack Down Flow utility heads with upper baskets (2) Riser Tubes