The Polypipe SPV110B Air Admittance Valve 4in/110mm is a high‑quality PVCu solvent socket valve designed for 110 mm soil/vent systems. Suitable for external use, it allows air into wastewater drainage and prevents foul gases from entering the building. Certified to BS4514 & EN1329, it’s ideal for 4‑inch soil stacks in commercial or domestic installations.