What is Medik8 Crystal Retinal 20 Medik8 Crystal Retinal 20 features next-generation retinal, clinically proven to work 11x faster than retinol to visibly smooth, brighten, and firm the skin. Unlike other products, our internationally patented stability system guarantees maximum retinal potency and effectiveness down to the very last drop. Thanks to our industry-leading encapsulation technology, you can achieve powerful results without irritation, even on sensitive skin. Recommended by professionals and dermatologists worldwide, our unique ladder of 5 progressive strengths allows you to continue experiencing enhanced benefits, effectively targeting stubborn fine lines, wrinkles, and dark spots.