A flat iron or curling iron spray that seals in the leave-In rescue Treatment & finishes the smoothing process. Hydrolyzed Keratin forms a durable, flexible "sacrificial" shield of keratin that reacts with sunlight & pollution to protect hair from damage & color fading. While sealing in your smooth style with heat tools, hair is protected from thermal damage up to 450?F & will remain smooth, soft & shiny for up to 72 hours (even in high humidity). To use: Section damp or dry hair & spray sections evenly, before using thermal tools.