This is the sock that put WRIGHTSOCK Double Layer on the map! Flat knit design with slightly heavier yarns to meet the rigors of your running regime. Ideal for a daily 3-mile run, or 50K race. If you want a little more volume in your shoe, Running ll socks should be your choice. Our Running Sock Features Recycled Polyester yarns improve moisture management and increased durability. Contoured shape and enhanced anatomically correct fit Stabilizer Zone(TM) in arch locks sock in place Blister-Free - No Blisters, Guaranteed! Blister-Free Running Socks Fiber Content These anti-blister running socks are composed mostly of eco-friendly Recycled Polyester. Recycled Polyester materials are made from recycled plastic bottles, helping you enjoy blister-free running adventures while protecting the ground beneath your feet. Inner Layer: 70% Recycled Polyester, 26% Nylon, 4% LycraA(R) Outer Layer: 68% Recycled Polyester, 24% Nylon, 8% LycraA(R) Double Layer Seamless Toe Wrightsock&';s Double Layer styles offer a seamless toe like most performance socks do these days; however, as you can see on the below images, Wrightsock&';s seamless toe looks a bit different. This is due to the required attachments that connect the inner and outer layers together for our Double Layer system. Even though it looks a bit odd, our seamless toe acts and feels the same on your foot as any other seamless toe design. Anti-Blister Running Sock Sizing Guide Finding the right fit is essential for blister prevention! You can view our sizing chart below. We invite you to contact us for any additional information or head to our FAQ page to find the answers to common customer questions. As an American-made, family-owned business, we thank you for choosing Wrightsock anti-blister running socks.