Premium Materials Every pair of Birkenstocks is made from the highest quality materials. Birko-Flor-Nubuck Upper / Classic Footbed - Suede Lined Birko-Flor Nubuck is the Birkenstock trade marked synthetic nubuck leather. Slightly porous with a matte finish and compressed felt backing. The essence of all our shoe models is the original BIRKENSTOCK footbed, which is inspired by the natural imprint of a foot in the sand and feels just like walking barefoot. Its anatomical shape ideally supports the natural walking action of your foot. Your feet, joints and back are protected. At the same time, your foot and leg muscles are exercised, and your health and well-being benefit as a result.