Nioxin Hair Booster is a treatment for the cuticle layer of the hair for hair that has become thin and brittle. This intensive leave-in treatment nourishes the hair and forms a protective barrier against damage to the cuticle layer. Formulated with KeraPro Complex to promote fullness, Hair Booster works on specific problem areas, such as a receding hairline or a crown with low density. Available in 2 sizes: 50 ml and 100 ml.