Sorel - Glacier Extreme (Black) - Men's: Durable water and wind resistant polyurethane backed 1000 denier Cordura(R)nylon. Drawstring with barrel lock closure. Integrated heel lock system. Removable 13mm ThermoPlus(tm)felt InnerBoot. Removable 13mm Sorel(R)Meltdown Midsole(tm); 2.5mm bonded felt frost plug in the shell to provide an extra layer of insulation and warmth. Handcrafted, waterproof vulcanized rubber shell. Aerotrac(tm)sole (natural rubber). Sorel Rated: -100F/-73.3C.