The BIRKENSTOCK Boston is a veritable classic that can easily be worn all year round. The Boston has a legendary status thanks to its sophisticated, individual design. The upper is made from extra-thick, oiled nubuck leather with an open-selvage finish. Oiled leather can be recognized by its untreated surface. BIRKENSTOCK purposely does not treat surface grains and other characteristic features. BIRKENSTOCK uses sturdy leather with a thickness of 2.8 to 3.2 millimeters as upper material.