The Resistance Force Architecte Mask by Kérastase is a professional treatment designed to strengthen and repair weakened, damaged hair. Its advanced formula deeply restructures the hair fiber, providing strength and resilience to fragile hair. Strengthens hair’s internal structure Repairs fragile and brittle areas Improves resistance to breakage Leaves hair soft and supple Protects against future damage HOW TO USE Apply a generous amount to washed, towel-dried hair. Leave on for 5 to 10 minutes depending on desired intensity. Rinse thoroughly. Use 1 to 2 times per week for optimal results.