Constructed from 1mm thick (20 gauge) Mild Steel Sheet formed to provide a 40/42mm thick fully flush, double skin door shell with lock seam joints at stile edges. Internal Reinforcements are provided at top, Bottom and Stile Edges. The inner core is a light weight first class quality PU Foam containing no asbestos or other inorganic fibres. Shutter is provided with 4mm thick plates welded inside at the place of hinges, locks and other hardware. Shutter have internal stiffeners to enhance strength.