The intensive restorative treatment Olaplex N°0 Intensive Bond Building Hair Treatment significantly strengthens weakened hair and prepares it for subsequent treatment with Olaplex N°3 Hair Perfector. Olaplex N°0 and N°3 form a two-step at-home routine that repairs damaged disulfide bonds in the hair and permanently strengthens the hair structure. It leaves hair soft, shiny, and more resilient.