Birkenstock Arizona "Soft Footbed" Birko-Flor Men's Sandals, Basalt, 43 M EU (US Men Size 10-10.5) Birko-Flor - a synthetic material made of acrylic and polyamide felt fibers that is comfortable and tear resistant. Synthetic sole Soft Footbed features an extra layer of cushioning foam built into legendary Birkenstock footbed. Birkenstock Arizona "Soft Footbed" Birko-Flor Men's Sandals, Basalt, 43 M EU (US Men Size 10-10.5) Anatomically correct cork footbed that is both renewable and sustainable. Birkenstock Arizona Basalt Birko-Flor Upper; Unisex Sandal. Arizona from Birkenstock is a classic two-strap style with fully adjustable straps and shock-absorbing EVA sole. Made in Germany by Birkenstock.