What It Is: A hyaluronic acid serum with an adaptogenic herbal complex that boosts radiance, protects against skin stressors, and visibly prevents signs of aging. What It Does: Kiehl's hyaluronic acid serum strengthens skin while helping defend against skin-aging stressors for youthful, radiant skin. These stressors include UV exposure, pollution and extreme temperatures along with tobacco, stress, lack of sleep and nutrition which can cause dullness, dehydration, fine lines and other signs of aging. This serum is clinically demonstrated* to double skin's strength** and helps visibly reduce fine lines, smooth texture and boost radiance for a healthy-looking glow. Clinically demonstrated to boost radiance by 29% and improve resilience by 38% for glowing, healthy-looking skin* Clinically demonstrated to visibly reduces fine lines by 27%* Clinically demonstrated* to double skin’s strength** Paraben-Free Absorbs easily with a lightweight texture For all skin types, including sensitive skin Active Ingredients: 11KDA HYALURONIC ACID - Hyaluronic Acid is known to help smooth and plump fine lines and is commonly used in skincare products to maintain moisture levels to boost hydration and visibly refine skin's texture. Our smallest molecular size of Hyaluronic Acid, 11kda, penetrates to fortify skin within its deepest surface layers.* By delivering hydration to skin’s most vulnerable layer, 11kDa Hyaluronic Acid helps better retain moisture for improved resiliency, suppleness and bounce. Adaptogenic Herbal Complex - a proprietary blend of adaptogens — Red Ginseng Root, Holy Basil and Schisandra Berry — traditionally used in Traditional Chinese, Korean and Ayurvedic Medicine. Within the formula, these adaptogens work synergistically to defend skin from stressors while renewing and resurfacing skin’s texture for a smooth, radiant appearance. How to Use: Apply onto cleansed face and neck, morning and night Can also be used under another serum Then apply a daily moisturizer *Based on a 4-week clinical study on 58 subjects tested in urban and polluted environments. **Based on Skin Strength Index = Composite average score of skin suppleness, plumpness and resiliency.