The Speedline PVCU Ext. XPS. Cavity Closer is a tailor-made solution for closing cavities around window and door openings in masonry walls. These 100mm x 2.4m single extension units are designed to provide a simplistic yet effective method of insulating and reducing cold bridging around the cavity. They are made from rigid extruded polystyrene (XPS) and encased in a durable, weather-resistant PVCU profile, ensuring longevity and reliability. Coming in a pack of 10, they offer excellent value for your construction requirements.