This flexible black rubber cover fits over the top of the sink drain to form a watertight seal between the disposal mounting ring and the sink flange. It is also known as a splash guard or a mounting gasket. It opens up in the middle and will allow you to feed water or food items into a garbage disposal while keeping liquids and smaller food particles from splashing back into the sink. This part is approximately 4 inches in diameter and is a genuine OEM part.