ISO-TOP WINDOW SILL FORMS are insulating profiles made from XPS polystyrene; this has very high compressive strength and was specially developed as thermal insulation for aluminium lower external window sills. This is always a critical area with respect to heat retention. The ISO-TOP WINDOW SILL FORMS do not simply offer excellent thermal insulation. They also provide a compression-resistant substructure for window sills made from aluminium or mineral materials. For further information: https://www.iso-chemie.eu/en/sealing