Prime your hair for your deepest at-home repair with this salon-inspired pre-treatment to boost the effects of No.3 Hair Perfector™. The highly concentrated formula rebuilds disulfide bonds to repair more severe damage and immediately strengthens hair when No.0 is used with No.3. How To Use: 1. On dry hair, apply and distribute evenly from root to tip. 2. Leave on for 10 minutes. Do not rinse. 3. Apply No.3 Hair Perfector™ and comb through. 4. Leave on for 10 minutes. Rinse well. 5. Shampoo and condition with No.4 and No.5. Ingredients: Water (Aqua/Eau), Bis-Aminopropyl Diglycol Dimaleate, Phenoxyethanol, Sodium Benzoate