The Professional Classic Series Ultra Low NOx water heaters combine efficiency with environmental responsibility, boasting a .58 - .64 UEF for reduced energy consumption and longer lifespan. Compliant with SCAQMD Rule 1121, they ensure minimal emissions, making them suitable for environmentally-conscious households. Available in 29, 39, 40, and 50 gallon capacities, these units offer versatile options to meet varying hot water demands efficiently.