Duckbill valve commonly known as: rubber discharge check valve, also known as: back-pressure flexible check valve, duckbill check valve, rubber check valve, check valve rubber, rubber slow closing check valve. The main models: XL-T, XL-F, XL-X type. The valve has no active components, avoid any maintenance. The valve can give straight pipe, flange pipe, concrete pipe, glass pipe support, the valve is widely used in coastal, beach, marina, reservoirs, municipal drainage, sewage, can be described as environmentally friendly green valve that beat replace doors, gates , completely solve the sediment, silt, rocks, vegetation, marine life blocking problems easily beat the door. Rubber duckbill valve prevents flooding and sewage flowing into the street sewers and basements intrusion, to avoid major losses, prevent the water level rises, flooding intrusion inflow of sewage treatment plants, pumping stations and drainage; stop sewage odor or smelly fluid diffusion, and can be drained at any time ; In the rainy season, to prevent the city from the river flood irrigation to the street sewer; quality is superior to shoot the door, shoot the door to overcome some shortcomings, such as closed lax.