Developed for flexible hold and protection against humidity, the Dyson Chitosan™ Post-style Serum Refill adds instant shine, definition and smoothness to the hair. Made with all hair types in mind, this lightweight formula is for use on styled strands as a finishing touch. It features a hyaluronic acid and amino acid blend to nourish, granting glass-like radiance to the lengths without adding any weight or residue. Plus Dyson Triodetic™ technology (powered by key ingredient chitosan) supports bond maintenance. Developed to defend against the effects of heat and harsh weather conditions, expect a secure style that lasts all climates.