The Opti.smooth Revitalizing Smoothing System contains pro-keratin, to strengthen the hair fiber and help prevent breakage to ultimately provide 25% more conditioner. • Pro-keratin is a complex of amino acids and proteins. This complex contains positively charged ingredients and is attracted to the negatively charged sites of damaged hair. • Attaches to damaged sites, helping to treat and revitalize the hair. This leaves hair stronger and better protected throughout the service.