We use Premium Cork Skin. Cork is harvested only every 9 years - this process helps the trees to grow, live longer and produce more oxygen. The material is not only extremely durable but also supple, being the perfect alternative to leather in every way. It is water resistant and flexible, so it will be a perfect fit to your daily use. The fact that it comes from the bark of a tree makes every product unique, so you may be able to appreciate some natural marks that shall not be deemed as defects but as a true statement of natural quality.