Waterproof upper in 600 Denier nylon. Gore-Tex membrane makes the shoe 100% waterproof and breathable. Removable 8mm Zylex liner made of 97% recycled material. Moisture-transporting inner part, adjustable snow lock with quick-release closure. Velcro closure that keeps the foot well in place and Niterays reflexes. Waterproof and durable lower part in synthetic rubber. Cold limit of -40 degrees.