The Endurance is our newest and softest Medium Cushioned Double Layer performance sock designed by runners who demand a blister-free and cushioned ride. Strategic cushioning hidden between the inner and outer layers eliminates running sock bulkiness! Blister-Free Sock Features Recycled Polyester performance yarns improve moisture management and added durability Stabilizer Zone(TM) to help lock the sock in place The new double tab design eliminates chaffing from the shoe, yet sits low on the foot (ankle high and Quarter length also available) Hidden terry loops buried between layers leave a smooth surface against the foot The softest, most comfortable run, walk, or workout you ever experienced! Blister-Free socks - No Blisters, Guaranteed Anti-Blister Sock Fiber Content These anti-blister hiking socks are made of sustainable RepreveA(R) Polyester. RepreveA(R) 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. Running Sock Sizing Guide Finding the right fit is essential for preventing blisters during your run! 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 sock business, we thank you for choosing Wrightsock.