Noritz NR50-ODNG Outdoor 5.0-GPM Natural Gas Residential Tankless Water Heater Outdoor model - NO VENTING REQUIRED 12 year warranty - Longer coverage than competition, 12 years on heat exchanger, 5 years on parts, 1 year labor Optional Freezing protection kit - Freezing protection kit is sold separately 0.5 GPM min. flow activation - Capable to handle higher incoming water temperature than current residential series 1/2-inch Gas fitting - NO NEED TO UPSIZE