How to Test: If your pool heater control board is incorrectly adjusting the temperature or the buttons on the MasterTemp control board pad don't work, the pad may need to be replaced. Works seamlessly with MasterTemp Pool and Spa Heaters, including models such as MasterTemp 400, 300, and 200, providing a convenient and versatile replacement solution. How to Fix: Peel back the membrane from your old pool heater control panel. Remove the sticker cover from the replacement pad and carefully apply it onto the heater cover. Slide the ribbon connector through and secure the connection. Location: The membrane pad is located on the heater cover of your MasterTemp unit. Consider taking a photo of the original positioning before removing the old membrane pad. Please note: Due to different production batches, the color of some parts may vary slightly. Color variations do not affect functionality, and slight differences in shade may occur. Color: As shown in photo Material: PC+PET Package Contents: 1 x Replacement Switch Membrane Pad Note: Light reflection and differences in display screens may cause the item's color to appear slightly different in images. Measurement may vary by +/- 1-3 cm.