OptiLight Window Slate Flashing - 78cm x 118cm A flashing is an essential element allowing correct installation of a roof window in the roof slope. The precisely designed systemic elements of the flashing enable tight and durable integration of the window with roofing. It is very important as the main task of the flashing is to drain water and snow away from the window and protect it against the wind. The flashings are manufacture from aluminium sheet, coated with hard-wearing polyester lacquer. The basic colour is Grey “ Brown (RAL 7022), which means windows go well with standard colours of roofing materials. For flat profile roofing materials up to 16mm such as: Slate & Shingles. These flashings can be only used with OptiLight windows.