Only the balance of the materials used can ensure long-term wear. We can't fit an upper that will fall apart within a year to the unique ISS sole with a lifetime of 5-7 years. Therefore, we only use long-lasting materials so that the shoes wear evenly. That is why we sew the uppers only in Slovakia, where there is a guarantee that the materials used are correct in appearance and mechanically, but they are also ecologically produced according to EU standards, which are strict, and that is also why these materials are more expensive as the upper material we use only bovine cheek leather, the linings are made of pig's cheek leather, or sheep or goatskin leather. In Dia shoes we use textile cotton and bamboo material Diatex of Czech production.