Protects and repairs damaged hair, split ends and frizz by re-linking broken bonds. A highly-moisturizing, reparative shampoo that leaves hair easy to manage, shiny and healthier with each use. Key benefits: Repairs and maintains bonds within the hair. Eliminates frizz and flyaways . Reduces breakage . This shampoo repairs and protects hair from everyday stresses—including damaged hair, split ends, and frizz—by re-linking broken bonds. N°4 is color-safe and proven to reduce breakage and strengthen all types of hair. Suitable for all hair types. Paraben-Free. Sulfate-Free. Phthalate-Free. **OLAPLEX products are thoroughly tested in-house and by independent third-party laboratories for safety and efficacy. This product testing includes the industry standard Human Repeat Insult Patch Test (HRIPT), which tests for skin irritation or sensitivity. All of OLAPLEX products passed the HRIPT, meaning the products show no signs of causing irritation, inflammation, or sensitivity. **