Retinol Benefits with COSRX The Retinol 0.5 Oil 20ml The Retinol 0.5 Oil: Formulated with 0.5% pure retinol for powerful anti-aging care. Ideal for skin accustomed to retinol but experiencing progressive signs of aging. Ideal for intermediate-level retinol users seeking a youth booster. Promotes smooth skin texture and visibly firm skin. No purified water or retinol derivatives.