K18 Leave-In Molecular Repair Hair Mask is a patented peptide hair mask to reverse damage from hair treatments.In just four minutes, this professional, salon-grade hair treatment from K18 Biomimetic Hairscience heals damage from bleach, color treatments, styling heat and chemical services. Formulated with a first of it's kind, patented oligopeptide, also known as K18Peptide™, this bioactive treatment reduces split ends, breakage and color fade, while restoring elasticity, bounce, softness and strength. Unlike conditioning treatments that hydrate the outer layer of hair and bonding treatments that wash out over time, this K18 hair product actually heals hair from the inside out and produces results that won't wash away.