Olaplex No.0 is a professional, science proven treatment that primes hair for an even more effective repairing treatment. The No.0 rebuilds hair bonds, and strengthens strands to keep hair healthy and free from damage and split ends. The No.0 was designed to give customers an at-home friendly version of their Professional back bar No.1 treatment which salons use to prep hair for absorbing nourishment and repairing strands following chemical treatments or to repair extremely damaged hair. The Olaplex No.0 contains the highest concentration of the brand's patented active ingredient, Bis Aminopropyl Diglycol Dimaleate, which helps to rebuild bonds, *leaving hair up to 3 times stronger and 68% more repaired. The formula is non-toxic, vegan and cruelty free as well as paraben and sulfate free, making it suitable and gentle on all hair types.