The Mobius Sia Mid is a strappy sandal with a hollow loop-shaped heel and a single band that forms the sole, heel, footbed, and upper of the shoe. The fiber-reinforced nylon heel is the strongest part of the shoe, while its open wedge shape keeps it incredibly light. United Nude's launch product, the Mobius, was revealed in 2003 and has since become an icon in the world of design. The style was born from a conceptual development of the Mobius strip, a single-sided surface with no boundaries. Its distinct shape was inspired by transforming the frame of Mies van der Rohe's Barcelona Chair into a single band, uniting the upper, sole, footbed and heel into one infinite piece.