FEATURES of the Sorel Men’s Glacier XT Boot Upper: Durable water and wind resistant PU coated synthetic textile upper. Drawstring with barrel lock closure Insulation: Removable 13 mm ThermoPlus felt inner boot with Omni-Heat reflective lining Midsole: 2.5 mm bonded felt frost plug. Removable 13 mm Sorel meltdown midsole Outsole: Handcrafted waterproof vulcanized rubber shell with Sorel aero-trac non loading outsole SPECIFICATIONS of the Sorel Men’s Glacier XT Boot Weight: 48 oz / 1384 g Temperature Rating: -100° F / -73.3° C