All OLAPLEX products contain the patented technology that strengthens fragile bonds at every step of the routine to make the hair as healthy as possible. Olaplex N°4P BLOND ENHANCER TONING SHAMPOO strengthens, softens and neutralizes unwanted yellow tints for lighter, more manageable hair. The sulfate-free, highly concentrated formula allows for customized tinting - the longer you apply the treatment, the lighter the result.Application:1.Apply to wet hair. Lather completely and leave on for 1-3 minutes. Rinse out. For a more intense tint, leave hair on for up to 5 minutes.2. Then use N°5 BOND MAINTENANCE CONDITIONER for daily moisturizing or N°8 BOND INTENSE MOISTURE MASK for additional moisturizing. Recommended TIP: Pre-wash with N°4 BOND MAINTENANCE SHAMPOO to remove product build-up.