The McAlpine VP1 Ventapipe 25 Air Admittance Valve is a plumbing fitting designed to provide a one-way air admittance valve for a drainage system. It features a 1½" BSP threaded outlet and is suitable for applications where a mechanical vent pipe cannot be installed. Made from high-quality materials, it meets relevant plumbing standards and can be used in domestic and commercial drainage systems. The one-way valve allows air into the system to prevent negative pressure buildup while preventing the escape of foul odors and gases. The 1½" BSP threaded outlet ensures easy connection to standard plumbing fittings for a secure, leak-free fit. This valve is reliable and effective, making it a valuable addition to any plumbing toolkit. Key features include a 1½" BSP thread on the outlet, A1 rating, and an air flow capacity of 3 l/s. Manufacturer: McAlpine.