Fill-in fiber contains small microfiber hairs that instantly adhere to the hair root, blending amazingly to help conceal Thinning Hair and bald spots. Simply shake the product directly over thinning areas of hair to disperse these small fibers into thinning areas for an instant fuller, thicker appearance of hair. Formulated with Procapil, a patented complex of natural botanicals, fill-in fiber not only fills in thinning hair and/or Balding Areas, it's also helping promote hair growth and prevent hair loss.