Birkenstock - Kalahari Rugged - Futura Black Birko-FlorKalahari Rugged is designed to bring Birkenstock comfort and support to your favorite trail and water based activities. These off road ready sandals feature a direct attach PU footbed, a rugged PU TPU outsole for added traction and sturdy hook and loop closures for a secure fit. The upper is made from the skin friendly, hard wearing synthetic material Birko Flor. Anatomically shaped PU footbed Upper: Birko Flor Futura Footbed lining: polyurethane