What it is a highly moisturising, reparative toning conditioner to neutralize brassiness and boost brightness for all blonde, lightened, and grey hair. Leaves hair easy to manage, shiny and healthier with each use. How it's different supports no.4p blonde enhancer toning shampoo to even out toning from root to ends hydrates and adds shine without weighing down the hair contains olaplex patented bond building technologytm to strengthen fragile bonds with every step of the routine for the healthiest hair possible. To use after cleansing with olaplex n?4p bond maintenance toning shampoo, apply a generous amount from scalp to tip. For more intense toning, leave on hair up to 3 minutes, then rinse. Olaplex products are thoroughly tested in house and by independent third party laboratories for safety and efficacy. This product testing includes the industry standard human repeat insult patch test hript, which tests for skin irritation or sensitivity. All olaplex products have passed the hript, meaning the products show no signs of causing irritation, inflammation, or sensitivity.