Redken’s Extreme Length Leave-In Treatment with biotin strengthens damaged hair and helps hair to grow longer and stronger. Extreme Length Leave-In Treatment helps prevent breakage to promote your strongest, healthiest hair. Reduces breakage by 81% when used as a full system with Redken Extreme Length Shampoo and Extreme Length Conditioner Visibly reduces the appearance of split ends by 78% Formulated with biotin and soy protein to help strengthen hair. Adds manageability, smoothness and shine.