Thrifco Plumbing 4405742 Kitchen Dishwasher Air Gap Cap (Flanged) – Satin Nickel Finish Brass

Air Cap prevents sewage from flowing back into the dishwasher. When water flows through the drain hose, it creates a suction on the water still in the dishwasher. The air gap, makes a hole for air to get in. That way, the water only leaves the dishwasher when it supposed to, when it is pumped out.