Stack flue sensor & heater thermistor compatible with for Pentair Sta-Rite, MasterTemp, Max-E-Therm pool and spa heaters electrical systems. Stack flue sensor & heater thermistor replace 42002-0024S, 42001-0053S. Stack flue sensor & heater thermistor made of metal, rust free material, easy to install, and sturdy to use. Before replacement, ensure that the power is turned off and wear work gloves to protect your hands. Colour:As Shown Material:Metal Due to different product batches, the appearance may vary, which does not affect the use Package Contents: 1 * 42002-0024S Stack Flue Sensor 1 * 42001-0053S Thermistor Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.