Olaplex N°4 Bond Maintenance Shampoo is a highly-moisturising, reparative shampoo that helps leave hair easy to manage, shiny and healthier looking with each use. No.4 is colour-safe and helps maintain bonds to strengthen all hair types and textures. How To Use Apply a small amount, to deliver nourishment and help improve strength and manageability. Use this Shampoo every time you wash your hair or after rinsing No. 3 from the hair.