Product information The fabric used for this mid cut is a cotton-linen blend. The high level of cotton (67% Cotonea Cotton) makes it especially robust and abrasion-resistant, while the hemp-flax fleece padding and soft flannel-linen lining also keep our feet warm and dry on cooler days. No animal-based materials are used in this model. Around 33% of the outer sole material is recycled, and the membrane is made of 100% polyester, 75% of which is recycled. Material Upper: Fantasy weave (67% certified organic cotton, 33% certified organic linen) – honey yellow Membrane: 100% polyester containing approx. 75% recycled material Lining / insole: Hemp-flax fleece (50% hemp, 50% flax) Interior lining / mid-sole: Flannel (100% certified organic cotton) Edging: Microfiber (100% polyamide) – honey yellow Outsole: 60% synthetic rubber containing approx. 33% recycled material, 25% silica, 15% recycled cork – toffee These are barefoot shoes, similar to Vivobarefoot or Xero Shoes. The shoes themselves are wonderful and I’d love to keep them, however they don’t fit me and I don’t want to pay to send them back to Germany. My loss is your gain. I generally wear a US 9/EU 40 and feel these run large (they were sold as a 9/41). I think they fit more like size 41.