Retinols are a non-prescription, non-irritating derivative of the Retinoid or Vitamin A family. The 15, 30 and 60 are arbitrary designations for creams containing 0.15%, 0.30%, 0.60%, and 0.90% percentages of Retinol and are generally targeted as tolerated to Sensitive Dry Skin, Element Exposed and Acne / Oily Skin types respectively.