Eco-friendly MasterTemp is certified for low NOx emission and outperforms industry standards . Its Best-in-Class energy efficiency and Tough, rustproof exterior handles the heat and weathers the elements. It is pre-wired for use with all major brand pool/spa automatic controls. Rotating digital display allows for easy viewing. Safe operation assured through a series of features, including: Water pressure switch that senses the pump is running to prevent overheating High limit switches assure heater turns off if water temperature exceeds factory-set limits Manual gas shut-off when service is required Stack flue sensor also guards against overheating Easy to install CPVS bulkhead connections; and reversible headers. The Master Temp comes with a low profile design with rounded corners. New MasterTemp heaters offer all the efficiency, convenience and reliability features you want in a pool heater, plus a lot more.