Pro Longer concentrate treatment for long hair helps thicken the apperance of long hair whilst making it visibly healthier and stronger looking. When used with the Pro Longer shampoo and Mask for long hair, there is a hair breakage reduction*. The Filler A-100 technology is patented to L\'Oréal Professionnel, and it works by penetrating the fiber core to plump and thicken the hair from the inside. The formula works on thin ends, or areas where help is most needed. *instrumental test, after application of Shampoo + mask + concentrate