Stable Retinal Night Serum Medium-Strength Vitamin A 4ml. Brand New. Unopened. Rediscover youthful-looking skin with Internationally patented Crystal Retinal 3, fortified with 0.03% encapsulated retinaldehyde, on advanced alternative to retinol. This overnight vitamin A serum-cream helps to diminish the appearance of fine lines and wrinkles while promoting a visibly smooth, clarified and radiant complexion.