Medik8 Crystal Retinal 20Medik8 Crystal Retinal 20 is an advanced nighttime serum formulated with 0. 2% retinaldehyde, a potent form of vitamin A that works up to 11 times faster than traditional retinol. This high strength serum targets fine lines, wrinkles, and uneven skin tone, promoting a smoother, more youthful complexion. Enriched with hyaluronic acid and glycerin, it provides deep hydration, ensuring skin remains plump and supple. Designed for experienced vitamin A