22" Straight Fineline Extensions by Hairdo have an unbelievable construction with a smooth and seamless application. Lightweight and comfortable, the kit consists of 4 pieces in 22 inch hair lengths extending to mid-back. The heat friendly synthetic hair fiber let's you create an individual look with the use of heat tools. 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.