Reduce the risk of foot, knee and back pain with this comfortable sandal. Sierra combines the comfort of the cork Birkenstock foot bed with the softness of the professional soles. The PU soles of these sandals are more flexible than the soles of the classic Birkenstocks. In addition, these soles are wear resistant, light and non-slip. The sturdy polyurethane sole is attached to the classic anatomically shaped cork foot bed. The two adjustable, brown straps of the Adventure Mocca are extremely soft for your feet. With this slipper, you avoid blisters due to irritation or friction. Sierra is the finer version of the Arizona. Birkenstocks have a large fit. You may need a size smaller than your regular size.