This microwave tray is also known as a turntable tray, a cooking tray, or a carousel. It provides a stable cooking surface for your food to sit and rotate on in the microwave. It is made entirely of glass, and is almost 13 inches in diameter. If your tray is cracked or does not rotate properly, your food will not heat evenly and you will need to replace it. You will not need any tools for this repair.