5th Avenue NYC. IPN: Interlock Protein Network. Fortifying care for distressed hair. Formulated to provide heat protection and help protect against breakage and split ends. Extreme Anti-Snap 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.