The Whirlpool WP3378134 Rinse Aid Dispenser Cap keeps the dishwasher rinse aid dispenser securely closed and supports proper dispensing during wash cycles. This replacement cap fits onto the rinse aid reservoir, providing a secure cover that helps maintain the dispenser’s seal and keeps the rinse aid contained. A properly fitted cap supports consistent rinse aid use and reduces the risk of leakage or spills inside the dishwasher door. A cracked, loose, or missing cap may affect dispenser function and allow rinse aid to escape.