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. Modeled on the cork sandals, it is made from the ultra lightweight and highly flexible synthetic material EVA. The high-quality, odor-neutral EVA has been tested for harmful substances and combines numerous positive attributes: it is very light, highly elastic, shock-absorbent, waterproof, and skin-friendly. Leather.