Types Of Glass/Glazing Used: Heat-reflective glass, safety glass, toughened glass, single glazing, double glazing, triple glazing. Type Of Material Used For The Frame: Steel, aluminium, wood (rarely used). The Number Of Panes And Their Mechanism: 2 panes (both movable), 2 panes (one fixed and one movable), 3 panes (centre pane is fixed while the other two are movable), 4 panes (two in the centre are fixed while the two at the ends are movable), sliding windows with a pane that tilts inwards, sliding windows with removable panes.