“This is the best shoe Xero Shoes has come up with thus far. It's made from recycled and biodegradable materials. The sole itself is smooth, but grippy and excellent for road-running. It's a real sustainable knockout.” – Jarvis C. Introducing the eco-friendly Zelen: comfort and sustainability come together in this zero-drop, minimalist road running shoe made with biodegradable and recycled materials. WHAT MAKES THE ZELEN THE IDEAL SUSTAINABLE RUNNING SHOE? EARTH-FRIENDLY. VEGAN-FRIENDLY. FOOT-FRIENDLY. The Zelen features a breathable knit upper made with rPET recycled material and a silky-smooth sock liner to keep you cool and comfortable mile after mile. The flexible yet durable 5.0 mm FeelTrue® sole features a tire-inspired tread to give you confident grip and control on asphalt, cement, and pavement – all without sacrificing the ground feel and feedback you love from Xero Shoes. The tension straps, made from earth-friendly recycled materials, are adjustable for added support and stability, allowing you to push further and faster. At a lightweight 7.9 oz per shoe in a men's 9, the barely-there feel of this sustainable runner will have you flying down the road yellin' “Zelen”! PERFORMANCE AND STYLE. The all-new Zelen is an eco-friendly performance shoe that's fast enough to tackle your next half-marathon yet stylish enough to pair with jeans, shorts, or just about any attire. Hit your next sprint in these, then hit your next guys' night. WE MAKE PERFORMANCE SHOES SO COMFORTABLE, YOU'LL FORGET THEY'RE EVEN ON. If your feet don't feel as good at the end of a run as they did at the beginning, you haven't tried the Zelen. Life-changing comfort and superior performance come from letting your feet do what's natural – bend, move, flex, and feel. All Xero Shoes feature a wider, foot-shaped toe box that lets your toes spread and relax. A non-elevated “zero drop” heel supports proper posture. The low-to-the-ground design promotes perfect balance and agility. And our flexible soles give you “just right” protection so you can bend, move, and flex while you Feel the World® in total comfort.