If the hair is damaged, its molecular structure consisting of peptides is weakened. But most peptides are too large to go back inside the fiber, so the damage is almost irreversible. For the very first time, scientists from the L'Oréal Advanced Research laboratories managed to break down the peptides and insert their individual parts into the hair fiber. Once inside, these parts can recreate and restore the hair's molecular structure. The patented composition of the L'Oréal Professionnel Serie Expert Absolut Repair Molecular leave-in mask, containing Peptides bonder and 5 amino acids, restores the molecular structure of the hair and visibly regenerates damaged hair from the first use. Hair is instantly soft, shiny and healthy looking.