This is a replacement cap for the detergent/rinse aid dispenser. If the rinse aid cap is damaged or missing, you may notice too much rinse aid in the dishwasher. The cap simply screws into the dispenser, so if your cap is damaged you can simply screw it out, then screw in the new one. The rinse aid cap is approximately 2 inches in diameter and is sold individually. This is an OEM part, directly from the manufacturer.