8mm ZYLEX® PERFORMANCE removable liner that wicks perspiration, traps body heat, and deflects outside cold. Waterproof and flexible synthetic rubber shell. SNOWAVEâ"¢ outsole maximizes traction. Also features adjustable belt around ankles and drawstring along collar to provide an even better fit. Temperature rated: -40°F/-40°C Click to see this boot in a wider width.