The Nioxin System 1 Liter Duo is for those wanting to thicken natural, lightly thinning hair. The shampoo (1L) delivers denser-looking hair, amplifies texture and removes build-up while providing an optimum scalp environment for more resilient hair. The conditioner (1L) delivers lightweight hydration and nourishment to the hair and scalp for stronger, thicker-looking hair. More effective when used together, this routine will help you achieve fuller, thicker hair.