How to Test: If your pool heater control board is incorrectly adjusting the temperature or the buttons on for mastertemp control board pad don't work, the pad needs to be replaced. Works seamlessly with for MasterTemp Pool and Spa Heaters, including models such as for MasterTemp 400, 300, and 200, providing you with the convenience of a single, versatile replacement solution. How to Fix: Peel back the membrane from your old pool heater parts. Detach the sticker cover from the new pad and carefully apply onto the heater cover. Slide the ribbon through and connect. Location: The membrane pad is located on the heater cover from your for mastertemp parts. Consider taking a picture of the positioning before taking off the old membrane pad. Please note: Due to different batches, the color of some parts of the actual product is random, and the specified color is not accepted. It does not affect the use, and the actual product may have slight color difference or difference Colour:Photo Color Material:PC+PET Package Contents: 1 x Replacement Switch Membrane Pad 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.