Hair Building Fiber are Natural Product is available in natural shades. Hair Building Fibers, made of colored keratin protein, blend undetectably with existing hair strands to instantly create the appearance of naturally thick, full hair. Features: Instantly fills in thinning areas. Conceals hair loss. Makes fine hair look completely thick and full. Great as a root touch-up What else you need to know Hair Fibers resist wind, rain, and perspiration for long-lasting results in all conditions. Available in Hair Fibers work for all hair types and textures. Also great for part lines, covering extension tracks and touching up roots between hair color appointments. Easily washes out with shampoo.