20 Gallon, Hybrid Gas Water Heater, 90% Thermal Efficiency, Hybrid Takes The Best Attributes Of Tankless & Storage Technologies, 20 Gallon Storage Tank Eliminates Sudden Interruption, The Sandwich Affect, Requires No Upgraded Gas Lines, Interactive Controls With Multiple Lifestyle Modes. A .70 EF Rating, Requires 15A, 115V Outlet, Kit Required For High Altitudes, Not Included, Use Kit #9007439005 For 3,501' to 6,500', Kit #900744005 For 6,501' To 8,500' & Kit #9007441005 For 8,501' To 11,000', 6 Year Tank & Parts Warranty.