After 1 Week, 98% Agree Skin Feels Softer*; Instantly, 83% Felt Refined Texture*; Smoother Skin in 1 Week**; Zone treat your face by applying Glycolic Acid Serum to areas prone to roughness. Follow with your favorite moisturizer where needed.; Use as an exfoliating treatment for cracked heels.; Layer with Kiehl's Hyaluronic Acid Serum to hydrate & rebalance skin’s moisture.; Layer with Kiehl's Niacinamide Serum to reduce oil & soothe skin.