Birkenstock Professional Birki Air 2.0 Clog Size 44 Regular Fit / Men's 11 Color: Jet Black Brand new with box. The new Birki Air 2.0 clog ushers in the next generation of Birkenstock’s Professional line with an innovative, fluid-resistant design. Side air vents help draw fluid away and improve breathability. With all the extras, like a detergent-friendly buckle, convertible backstrap and contoured PU footbed to support you through long hours on your feet. Contoured PU footbed, antistatic Fluid-resistant PU upper with side air vents Microbfiber footbed lining PU sole is antistatic, oil- and grease-resistant Convertible backstrap, detergent-friendly buckle