The Birkenstock Boston has earned its cult status with its simple, comfortable design. This edition upgrades the classic with smooth natural leather uppers, while the cork-latex footbed and cushioned EVA outsole deliver the same legendary support. Natural Leather Upper, Anatomically Shaped Cork-Latex Footbed, Suede Footbed Lining, Adjustable Strap, EVA Outsole, Made in Germany, Birkenstock. Birkenstock Men's Boston Concrete Grey Smooth Leather.