SHIELD: This leave-in serum forms the fourth and final step in the new Bond Repair haircare routine for stronger hair with maximum shine and heat protection. A finishing touch to create maximum softness and shine, this serum smoothly shields the hair bonds to result in 12X fewer split ends.Hair is made up of millions of bonds that give it structure and strength. When hair bonds break, through brushing, bleaching, heating, and styling, hair becomes weak and damaged. For the first time, our formula powered by Citric Acid Complex targets damaged hair. Up to 12x less split-ends¹, 98% stronger hair² & 82% more shine². Suitable for all types of damaged hair. ¹ instrumental test after 5 applications of Pre-Shampoo Treatment + Shampoo + Conditioner + Leave-In Serum.² instrumental test after application of Serum.