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 N°3PLUS Complete Repair Treatment and comb through. 4. Leave on for 10 minutes. Rinse well. 5. Shampoo and condition with Nº.4 Bond Maintenance® Shampoo and Nº.5 Bond Maintenance® Conditioner. Prime your hair for your deepest at-home repair with this salon-inspired pre-treatment to boost the effects of N°3PLUS Complete Repair Treatment. The highly concentrated formula rebuilds disulfide bonds to repair more damage and immediately strengthens hair when N°0 is used with N°3PLUS.