The McAlpine VP50 Ventapipe 50 is an air admittance valve designed for use in plumbing systems to prevent the loss of water trap seals due to negative pressure. The valve features a 2" universal outlet, which allows for the discharge of waste water from a variety of sources, such as sinks and baths. Similar to other air admittance valves, the VP50 is a one-way valve that allows air to enter the plumbing system, but does not allow gases to escape into the living or working space. This is important for maintaining a healthy and safe environment, as sewage gases can be harmful to health.