This is a dishwasher air gap assembly. This plumbing device is installed to prevent contaminated water from the sink drain or garbage disposal from flowing back into the dishwasher. 

• It is a replacement for existing deck dishwasher air gap assemblies. 

• The assembly includes the main body (white) and the cap (black). 

• The device has no moving parts and uses atmospheric pressure to protect from backflow contaminants. 

• It is a required component in some plumbing codes to ensure public health safety.