SSR1-5 Features: -Pool / spa heater. -Converts sunlight to heat. -Rings are joined together with magnets. -Limits evaporation of pool water and chemicals. -All you need to do is cover 60% – 70% of your pool. Product Type: -Pool/Spa. Heater Source: -Solar. BTU: -200,000 – 250,000. Generic Specifications: -Each ring produces up to 21000 BTU of energy every day.