This Microwave Light Bulb is a replacement part for the exterior bulb that mounts on the bottom of the appliance to illuminate the cooktop. If your lower microwave light is burned out, you can easily replace it with this item. The part is a 40-watt bulb with a small screw-in base. Installation will require basic hand tools, minor disassembly of the microwave and novice repair experience. You must unplug the microwave or shut off the house circuit breaker for the appliance before installing this part. Helpful Tip: If the blown bulb's threads are corroded, the socket may also need to be replaced.