Product Description The Danco air cap prevents sewage from flowing back into the dishwasher. When water flows through the drain hose, it creates 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. From the Manufacturer Danco is one of the largest plumbing repair, replacement and remodel suppliers in the home improvement industry.  We are largely focused on empowering Do It Yourself consumers with affordable plumbing products and solutions which create new and refreshing décors for bathrooms and kitchens.