LDR 1-1/2 in. D Stainless Steel Air Gap Replacement Cap

The LDR 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.