Xero Shoes Barefoot Sandals - Men's Amuri Venture Synthetic rubber Enjoy Xero Shoes for walking, hiking, biking, yoga, working out, paddle boarding, water sports, jogging, running, and even 100-mile ultra marathons. 5.5mm non-marking, non-slip, FeelTrue sole for total natural movement with just-right protection. The only outsole made specifically for barefoot-style sandals. Patent-pending, easy-adjust lacing holds comfortably on your foot without pressure points common in flip-flops. Lightweight and flexible enough to fit in your pocket, pack or purse. Soles have a 5,000 mile warranty NOTE: To guarantee a correct fit, please measure your foot: 1) Place a piece of paper on the floor, against a wall; 2) Step on the paper, your heel against the wall; 3) Mark the paper in line with your longest toe; 4) Measure that length with a ruler; 5) Compare that length to the sizing chart (link, above). To REALLY ensure a correct fit, get printable templates of the exact sizes by contacting the Seller.