Compatibility42001-0063s Water heater High Limit Switch replacement For Pentair Mastertemp (400 /200 /300/125)Sta Rite Max-E-Therm (Sr200 / Sr333 / Sr400) Pool Heaters models Also apply to Sta Rite/Mastertemp Pool Heaters models The switch monitors the temperature of the Pentair pool heater and automatically turns off the gas supply when the temperature exceeds 135F (71C), protecting the heater from heat damagePart replacement number42001-0063S, 42001-0064S, HMXHLI2932, HAXHLI1930, STA-151-625High quality material42001-0063S water heater high temperature limit switch is made of high quality metal, with high strength corrosion resistance, high temperature resistant material, each product has undergone strict pressure, temperature, and air tightness test to ensure normal and safe operation under any conditionsTrouble shootingWhen the HLS LED indicator lights up, it is a reminder that you need to replace the high temperature limit switch. HLS is short for "high temperature limit switch", and the upgraded Pentair motherboard will also display HLS on the main display, so that there is no problem of failureEasy to installFirst turn off the water pump and all the power to the pool heater high temperature limit switches located on the black manifold inside the heater, insert the connector into the hole, and the pool heater starts again to save you the cost of replacement and repair