Kérastase Resistance Ciment Thermique is a heat-activated blow-dry primer for weakened & damaged hair. This lightweight leave-in treatment strengthens & fortifies hair after just a single use & offers up to 87% less breakage. Say goodbye to split ends & cracks & hello to added shine & smoothness. The special Vita-Ciment & Topseal formulas work together to strengthen hair fibres from the inside & recreate an external protective layer that not only strengthens but also prevents further weakening from heat styling.