Repairs, strengthens, & nourishes all hair types. N°4 Shampoo repairs and protects hair from everyday stresses — including damaged hair, split ends, and frizz — by re-linking broken bonds. Leaves hair easier to manage, shinier and healthier with each use. N°4 is colour-safe and proven to reduce breakage and strengthen all types of hair. How To Use: 1. Use every time you shampoo OR after rinsing Olaplex No.3 Hair Perfector from hair. Lather. Rinse. 2. Follow with Olaplex No.5 Bond Maintenance Conditioner. 250ml