Rheem PROE20 1 RH POU Professional Classic Residential 20 Gallon Electric Point-of-Use Water Heater Exclusive tank lining resists corrosion and prolongs tank life Meets or exceeds National Appliance Energy Conservation Act (NAECA) requirements These units are U.L. listed and comply with Underwriter's Laboratories Specifications 174 Enhanced-flow brass drain valve on 2.5-gallon model This new Model number replaces the old Model number 81VP20S