Dewalt 5140204-46 Compressor Check Valve is used to control airflow and prevent backflow within compatible air compressor systems. It works by allowing compressed air to flow in one direction while preventing air from returning to the compressor pump or tank. A properly functioning valve supports consistent pressure retention, reduces air loss, and maintains reliable compressor operat... https://www.wholetoolbox.com/dewalt-5140204-46-compressor-check-valve/5140204-46.html