After cleansing you may use this serum as the first step of skin care. Spread the serum on the entire face and you may apply several times to amplify the effect of the next serum or ampoule. [/Skin Barrier Boost/] + Advanced Snail 96 Mucin Power Essence : Light-weight essence which absorbs into the skin fast to give skin a natural glow from the inside. [/Wrinkle care Boost/] + The Retinol Cream : An irritation-reduced solution created with the optimal ratio of key ingredients for first-time retinol users just starting to notice the appearance of fine lines caused by dry skin. [/Brightening Boost /] + The Vitamin C 23 Serum : A highly concentrated serum that fades acne scars and brightens the complexion to revitalize dull and dry skin. [/Acne care Boost/]+ The Niacinamide 15 Serum : Highly concentrated serum that combines the maximum concentration of niacinamide with optimal ratios of synergistic ingredients for total acne control. [/Hydrating Boost /] • The Hyaluronic Acid 3 Serum 20ml / 0.67 fl. oz : Highly concentrated 3% hyaluronic acid serum that hydrates, plumps, soothes and supports the skin's moisture barrier.