Don't let thinning hair hold you back! Cover Your Gray Pro Fill-In Fibers can help you regain your confidence, effectively concealing your thinning hair. Fibers adhere to hair root to help conceal bald spots. Thickens thinning hair INSTANTLY! Easy to apply. Formulated with Procapil, a patented complex of natural botanicals, Fill-In Fibers not only fills in thinning hair and/or balding areas, it also works to help promote growth and prevent hair loss.