This is called a magnetron and it is to be used in your microwave. The purpose of this part is to generate energy and heat for your appliance. This piece is 6 inches long, 6 inches wide, and 5.5 inches thick. The most common reason for needing to change the magnetron is if your appliance is making loud noises and does not heat. Before making this repair, we recommend unplugging your microwave and letting it sit inactive for some time. Take precautions while making this installation as a microwave can hold a lethal electrical charge for extend periods of time, even when unplugged.