Duckbill valves are a type of one-way valve that allows fluid to flow in only one direction, it has a unique design, which resembles the bill of a duck. When fluid flows in the correct direction, the valve opens, allowing the fluid to pass through. When fluid tries to flow in the opposite direction, the valve closes, preventing any backflow. They are made from elastomeric materials, s... https://www.yejiasilicone.com/duckbill-valves/