This Serie Expert Absolut Repair Molecular Leave-In is a patented no-rinse hair mask formulated with bond repairer + 5 Amino Acids that repairs the hair's macromolecular structure. When hair is damaged, its molecular structure, made up of peptides, is compromised. But most of the peptides are too large to be injected back into the fiber, which makes the damage practically irreversible. For the first time, L'Oréal Advanced Research has managed to break down the peptides to inject their components separately into the fiber. Once inside, they reform and rebuild the hair's macromolecular structure. 100ML EXP. 12 months from opening date.