The Gorge Winter Waterproof Boots will keep your feet warm and protected during hikes, treks and long country 10k. With IsoDry technology to keep your feet dry during wet weather, and an IsoTherm lining tested to temperatures of -10°c. IsoDry - Waterproof & breathable material allows moisture out & prevents rain getting in. TPR Rubber - Lightweight and durable material. Thermal Tested -10°C - Laboratory tested. Health, physical activity & perspiration will affect performance.