SkinCeuticals Glycolic 10 Overnight TreatmentGlycolic 10 Renew Overnight is formulated with a free acid value of 10% glycolic acid, allowing it to work at a true 10% concentration proven optimal in promoting effective exfoliation and natural cell turnover. Free acid value refers to the true strength of a glycolic acid product, and is affected by both the concentration of acid and the pH of the formula. This potent night cream is synergistically blended with 2% phytic acid to promote skin clarity