Our warmer waterproof design. Mid-calf height (11''). Three layers, securely bonded together throughout inner lining: expedition-weight double velour Polartec Power Stretch fleece, between: our stretching waterproof, breathable MVT membrane, outer shell: Nylon/LycraSpandex offering a durable , flexible, stretch covering. Stretch-to-fit to avoid uncomfortable sags and wrinkles, even in strenuous activity. Seamless design provides the ultimate in performance and comfort without annoying ridges and pressure points. Each sock is high-pressure tested to ensure that has no leaks.