OLAPLEX Patented Bond Building Technology™ strengthens fragile bonds with every step of the routine for the healthiest hair possible. This ultra-light volumizing shampoo for fine hair is clinically proven to strengthen, repair, and prevent future damage from everyday elements, styling, or salon services.* The best shampoo for fine hair has to repair as it volumises. No.4 Fine gently removes build up to leave hair clean and soft with lasting volume, body, and bounce – never weighed down or dried out.