Introducing K18 Biomimetic Hair Science with the K18 Leave-In Molecular Repair Hair Mask! 10 years of biomimetic hairscience research led to the discovery of a unique sequence of peptides, patented K18 Peptide. This leave-in formula brings chemically damaged hair back to its youthful, healthy state by reconnecting broken keratin chains caused by chemical or mechanical damage. K18 Hair Mask Benefits: This mask has a wide range of restorative benefits, The results are soft, smooth, repaired, and strong hair with luxurious bounce & shine! Clinically proven to restore, strengthen and improve the elasticity of the hair in just 4 minutes.