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 bulkiness! Blister-Free Running Sock Features: Recycled Polyester performance yarns improve moisture management and added durability Stabilizer Zone(TM) to help lock the sock in place Hidden terry loops buried between layers leaves a smooth surface against the foot Eco-friendly and made in the USA The softest, most comfortable run, walk or workout you ever experienced! Blister-Free socks - No Blisters, Guaranteed Fiber ContentInner 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 Sock Sizing Wrightsock knows that one of the easiest ways to fight blisters is to find the right size. You can view a visual overview of our sizing below, or read our full sizing information with care instructions here. We also invite you to visit our FAQ page with any additional questions you may have or contact our experts for further information. Thank you for choosing Wrightsock!