Kingspan Kooltherm Cavity Closer is a PVC–U extrusion with a rigid thermoset insulation core that provides a simple and efficient method of closing cavities around openings in cavity walls. Available in 125mm or 150mm options it can be trimmed down to ensure a snug fit between masonry leafs.It is suitable for use with timber, metal or PVC window frames and passes the one–hour fire test.