Metalwork Plastic & Brass Flow Control Valve, 90 Degree Male Elbow With Push to Connect Quick Connector, 8mm Tube OD x 1 4" BSP Male Thread (Pack of 2) 8mm OD x 1 4" Male Pack of 2 industrial Pressure compensation design Pressure compensation June_2023_update Pressure compensation design Pressure compensation drippers are suitable for a variety of complex irrigation conditions Package include: 2PCS alligator clips test leads or other fluids between pipes Control valves sometimes include either a ball cone (which utilizes a spring loaded ball seated against a cone shaped interior surface to block the flow) or a swing check valve (which has a movable disc on a hinge to block reverse flow)