This vitamin STEP-UP SYSTEM of serums has been formulated with the highest concentration of vitamin a. They are designed to help normalise the appearance of skin abnormalities and damage, and in promoting healthy looking skin eventually creating skin that looks truly reborn and beautiful. Only used on skin already acclimatised to AVST 5/or C-quence 4 introduces skin to highest doses of vitamin A ,introduce very slowly ,follow with environ vitamin A cream and SPF.