Bradford White Defender Safety System®, 50 Gallon Standard Residential Gas (Liquid Propane) Power Direct Vent Water Heater. 6-Year Tank Warranty, 38,000 BTU/Hr., 120 Volts, Single Phase, with Power Cord included. The -475 indicates that this SKU was designed to operate in Altitudes between 2,001 feet and 7,000 feet.