Bain Extentioniste for strengthening hair fibers. Thanks to Kérastase's Bain Extentioniste, you can restore strength to your weakened hair fibers, cleansing and giving them shine. This shampoo from Kérastase also accelerates hair growth, promoting long and healthy hair. Enriched with valuable ingredients like Creatine R and Taurine, the shampoo enhances the elasticity and resilience of the hair and is responsible for a healthy scalp.