Birkenstock Silver Glitter Boston Clogs Size 39 (8.5) Has some wear, see pics. The BIRKENSTOCK Boston Clog is a true classic that can be easily worn throughout the year. This extravagant version is covered with glitter and lined with a particularly cozy lambskin insole. The upper material consists of the skin-friendly and durable synthetic material Birko-Flor®. Anatomically shaped cork/latex footbed Upper: Birko-Flor® Footbed lining: lambskin