Style 40793 in black Birko-Flor, 40413 in silver Birko-Flor, or 240863 in white patent Birko-Flor. Birko-Flor - a synthetic material made of acrylic and polyamide felt fibers that is comfortable and tear resistant. This material has a synthetic leather-like finish with felt lined backing. Birkenstock narrow footbed. Wipes clean with mild soap and water. EU sizes 36-41 equivalent to US sizes 5-10.