Sta-Rite SR200NA Max-E-Therm Pool And Spa Heater, Natural Gas, 200,000 BTU Lightweight - Lightest heater in its class Compact Design - Ideal for retro-fit installation Lower Operating Costs - 84% efficiency rating - rated 1st in its class for highest energy efficiency Rustproof Housing Sleek, matte black enclosure is made of Dura-Glass - an exclusive Sta-Rite material that handles the heat and weathers the elements