This hair mask for long hair helps thicken the hair for visibly healthier & stronger looking lengths. When used with the Pro Longer shampoo & ends-filler treatment for long hair, split ends are reduced visibly by 66%. The Filler A-100 technology used is patented to L' OrÉal Professionnel, & it works by penetrating the fibre core to plump & thicken the hair from the inside. Amino acids in the formula work to strengthen the hair from the outside. The formula works on thin ends, or areas where help is most needed.