Medik8 Crystal Retinal 6Medik8 Crystal Retinal 6 is a powerful nighttime serum with 0. 06% retinaldehyde, a high strength form of vitamin A that works up to 11 times faster than standard retinol. Its designed to target fine lines, wrinkles, and uneven skin tone, leaving your skin smoother and more youthful. Enriched with hyaluronic acid and glycerin, this serum hydrates deeply, keeping your skin plump and soft. Ideal for those who have used vitamin A before, Crystal Retinal