The Olaplex No.4 Shampoo and No.5 Conditioner are part of the Olaplex Bond Maintenance? system, designed to repair, strengthen, and moisturize all hair types. Here's what each product does: Olaplex No.4 Bond Maintenance Shampoo: This shampoo cleanses the hair while maintaining the bonds that were repaired and strengthened by Olaplex treatments. It helps to restore internal strength and moisture levels to the hair, leaving it feeling soft, smooth, and healthy. Olaplex No.5 Bond Maintenance Conditioner: The conditioner helps to detangle, hydrate, and protect the hair, reducing frizz and flyaways. It nourishes and strengthens the hair, leaving it more manageable and resilient to damage. Additionally, you mentioned the No.2 treatment, which is the Olaplex Bond Perfector. This is typically used in salon settings as a standalone treatment or following the application of Olaplex No.1 Bond Multiplier during chemical services like coloring or lightening. It helps to further repair and strengthen the hair's bonds, ensuring maximum protection and vitality. Together, this trio provides a comprehensive system for repairing and maintaining the health of the hair, particularly beneficial for those with chemically treated or damaged hair.