Toppik's Hair Building Fibers - Gray blend in seamlessly with existing natural hairs to create a fuller, thicker appearance. Crafted with colored keratin protein, these gray hair-building fibers fill in thinning areas, cover part lines, conceal extension tracks, and touch up roots.Resistant to wind, rain, and perspiration, these hair-building fibers are suitable for all-day wear, and they wash out easily with standard shampoo.