Molecular Repair Leave-In Mask. This patented bioactive peptide treatment strengthens and improves elasticity while permanently repairing damage from chemical treatments, heat styling, and heat styling tools. Hair feels renewed. This leave-in mask repairs and strengthens hair with lightweight moisturizing agents to detangle and keep hair smooth and soft without weighing it down. For all hair types. Benefits: K18Peptide™ is the molecular innovation hair care has been waiting for, clinically proven to permanently repair hair in just 4 minutes.