Metal building materials; including metal window frames, particularly extruded window frames of aluminium; metal window panels; metal door frames, particularly of aluminium; door panels of metal; aluminium extrusions; aluminium doors and windows; metal framed awning windows, casement windows, bay windows, horizontal and vertical sliding windows, box windows, bi-fold windows, greenhouse windows, roof windows and skylights; window and door jambs, stiles, sills, heads, mullions and transoms all of metal; sliding sashes of metal for windows and doors