L'Oréal Professionnel's Pro Longer concentrate treatment is designed to thicken long hair for a visibly healthier and stronger looking appearance. When used with the Pro Longer shampoo and ends-filler treatment for long hair, split ends are reduced visibly by 66%. * The unique Filler A-100 technology works by penetrating the fiber core to plump and thicken the hair from the inside. Amino acids in the formula work to strengthen the hair from the outside. The formula is particularly effective on thin ends or areas where help is most needed. It renews lengths, fills in ends, enhances shine, minimizes breakage and split ends, and thickens long hair. The result is hair that looks visibly healthier and stronger. For best results, apply to damp hair before using Pro Longer shampoo, leave in for 3 to 5 minutes, and then rinse thoroughly. The formula contains Aqua / water / eau, aminopropyl triethoxysilane, lactic acid, peg-40 hydrogenated castor oil, polyquaternium-6, phenoxyethanol, and citric acid.