Birkenstock Arizona 2-Strap Birko-Flor Sandals, Basalt (Dark Grey Blueberry Blue), 39 M EU (US Women Size 8 to 8.5) Birko-Flor Synthetic Upper. Birkenstock Arizona Birko-Flor Sandals, Basalt (a Dark Greyish/Blueberry Blue like color), Unisex, 39 M EU (US Women Size 8 or US Men Size 6) Birkenstock Arizona Black Birko-Flor Upper; Unisex Sandal. Arizona from Birkenstock is a classic two-strap style with fully adjustable straps and shock-absorbing EVA sole. Anatomically correct cork footbed that is both renewable and sustainable. Suede-lined, contoured footbed will mold to the shape of your foot. Raised toe bar designed to encourage the natural gripping motion of your feet.