- Keratin Hair Fibers that blend and cover thinning and low-density areas of hair for instant Thicker Fuller-Looking Hair. Hair Thickening Fibers are Keratin Proteins similar to natural hair. Hair Thickening Fibers blend with natural hair that may add density and help create Thicker Fuller-Looking Hair. Creates instant Thicker Fuller-Looking Hair. Covers-up fine and thinning areas of hair. Perfect for cover-up between color treatments. Made from Keratin Protein. Keratin Fibers: Fibrous structural proteins, the key structural component of hair and nails. The fibers are charged with static electricity so they intertwine and bond with your own hair. Easy Application: 1.HAIR MUST BE COMPLETELY DRY. 2.Brush or comb hair, shake Hair Thickening Fibers applying liberally into thinning and low-density areas. 3.Gently style hair into place with fingers or plastic comb. 4.If desired, use Brush Applicator filled with Hair Thickening Fibers to apply around hairline and hard to reach areas. 5.Spray Bosley Professional Strength Non-Aerosol Hairspray & FiberHold Spray, which may increase the bond between natural hair and Hair Thickening Fibers for extra durable, longer-lasting style. 6.Shampoo to remove.