Feder blueBuy Now The sandal's upper is made of durable microfiber, which protects the foot while giving it as much freedom of movement as possible. The design relies on a delicate fit and few individual parts. Thanks to the integrated heel loop, the sandal requires very few seams. This saves resources and contributes to the durability of the lightweight. We owe the fact that the sandal offers great grip with very little material to the so called windlass