Newer developments have increased the thermoplastic family for the lamination of glass. Beside PVB, important thermoplastic glass lamination materials today are ethylene-vinyl acetate (EVA), thermoset EVA ethylene-vinyl acetate (EVA) and thermoplastic polyurethane (TPU). The adhesion of TPU is not only high to glass, but also to polymeric interlayers. Since 2004, metallised and electroconductive polyethylene terephthalate (PET) interlayers are used as substrate for light emitting diodes and laminated to or between glass. Coloured interlayers can be added to provide a permanent transparent colour for a laminated glass panel. A switchable interlayer can also be added to create a panel which can be clear when a small electric current is passed through the interlayer and opaque when the current is switched off. This is commonly known as privacy glass.