Clean, vegan 2.5% Bio-Retinol + Retinol serum with breakthrough scientific technology encapsulating the vitamin in Evening Primrose to assure stability and to avoid toxic chemicals. Skin-rescuing technologies to help keep your skin looking and acting youthful while you sleep. This serum glides on smoothly and leaves skin feeling hydrated. After cleansing with a STEM CELLULAR Cleanser, apply at night to face, neck and décolleté. Limit initial use to once or twice a week, gradually increasing frequency to every other night and then every night as tolerated. Follow with STEM CELLULAR Anti-Wrinkle Moisturizer or STEM CELLULAR Anti-Wrinkle Overnight Cream. Always use a broad-spectrum sunscreen such as STEM CELLULAR CC Cream with SPF 30 during the day when using retinols + bio-retinols.