100% virgin PVC-u (Polyvinyl Chloride Unplasticised). Fully welded system (corners, transoms and mullions).   10 year anti-discolouration guarantee. Double glazed sealed units, manufactured to copmly with BS5713 Toughened units (comply with BS6206) if window falls below 800 mm (internal floor). Internally beaded system; prevents external removal of glass by a potential intruder. Push-to-open key locking handles (available in white, gold and chrome at no extra cost). Multi-point shootbolt locks with night vent facility. Positively locating stainless steel friction stays (hinges). Fire escape hinges also available, if required (extra cost). Twin weather sealed low-lying gaskets. mahogany light oak rosewood. Woodgrain finish (either inside and outside or outside only). Georgian bar matrix (fitted inside the sealed units for ease of cleaning). Astrical Georgian bar matrix (fitted to outside of outside pane and outside of inside pane). Square/diamond lead (fitted to the inside and outside of the outside pane of glass). Stained lead designs (ask for details, as many options are available).