Olaplex No.0 Intensive Bond Building Hair Treatment is a professional at-home treatment that primes hair to repair broken and weakened bonds. This concentrated formula significantly strengthens, softens, and protects the entire hair structure. It works by relinking the disulfide bonds broken through chemical, thermal, and mechanical damage, preparing the hair to receive maximum benefits from the Olaplex No.3 Hair Perfector treatment that follows. Use this intensive step to revitalize severely damaged hair and maintain overall hair health. Ideal for use as a pre-treatment before your regular intensive hair mask or bond builder.