The McAlpine VP1 Ventapipe 25 Air Admittance Valve is a plumbing fitting that is designed to provide a one-way air admittance valve for a drainage system. It features a 1.5" BSP threaded outlet and is suitable for use in applications where a mechanical vent pipe cannot be installed. The Ventapipe 25 is made from high-quality materials and is designed to meet all relevant plumbing standards. It can be installed in a wide range of applications, including domestic and commercial drainage systems. The one-way air admittance valve feature of the McAlpine VP1 Ventapipe 25 ensures that air can flow into the system to prevent the buildup of negative pressure, but prevents the escape of foul odors and gases into the environment. The 1.5" BSP threaded outlet of the McAlpine VP1 Ventapipe 25 makes it easy to connect to standard plumbing fittings and fixtures, and ensures a secure and leak-free connection. Overall, the McAlpine VP1 Ventapipe 25 Air Admittance Valve is a reliable and effective