IPN: Interlock Protein Network. Fortifier for distressed hair. Protein/ceramide. Detangles, strengthens and protects distressed hair. Extreme Conditioner with Interlock Protein Network and Fortifying Complex delivers protein and ceramide to help fortify weakened areas, protect internal strength and reinforce surface protection and shine. Hair is healthy-looking and resilient. Safe for color-treated hair. redken.com. Guaranteed only when sold in salons. Made in USA.