22" Wavy Fineline Extensions by Hairdo has the perfect amount of hair with the perfect wave. Fine hair is a thing of the past with extensions made just for that. These 4 pieces with a seamless edge are so light you'll forget you have them on. The heat friendly synthetic hair let's you touch up the wave, or change it up. With Fineline construction, the hair is stitched to a fine layer of polyurethane, resulting in thinner, lighter and virtually undetectable pieces that lay flat to the head for a more natural appearance.comfortable, natural looking effect.