For heater that developed a problem where it constantly cycles on and off when temperature is reached. Simply replace the pool heater thermostat control to eliminate the issue of water taking too long to heat up. The STA thermistor has undergone extensive testing, providing a reliable thermal regulator to help keep your pool or spa heater operational, quickly warm the water, and reach the desired comfortable temperature. This 77707-0010 thermal regulator is made of high-quality metal, effectively resisting corrosion and rust, significantly extending service life, even in saltwater environments. The thermal regulator kit is designed for use with Master Temp, Sta-Max-E, and other compatible pool and spa heaters. It is installed between the inlet and outlet water connections on the water manifold. The kit includes regulator, spring, and cap. Color: As shown in photo Material: Composite materials Package Contents: 1 x Thermal Regulator Kit Note: Light reflection and different display settings may cause slight variations in color between the image and the actual item. Measurement allowance is +/- 1-3 cm.