20" Invisible Hair Extension by Hairdo is a heat friendly halo hair extension that provides length, volume and can give you additional colour dimensions... all on an invisible stretch thread. Heavenly hair isn’t just for runway models and Hollywood starlets anymore. Get mega-watt length and volume in seconds with this 20 inch halo extension. Just slip it on like a headband and pull your own hair over it‐the subtle design blends seamlessly with your hair, and the synthetic heat friendly fibers can be heat styled to create any look.