Sorel Youth Caribou Boot - - Often imitated but never equaled, the original Sorel boot features waterproof construction, seam-sealing and a removable ThermoPlus? felt inner boot for warmth, comfort and protection in cold and went winter weather. THE CONSTRUCTION Seam-sealed waterproof construction. UPPER: Waterproof nubuck leather upper. INSULATION: Removable 9mm ThermoPlus? felt InnerBoot with Sherpa Pile? snow cuff. MIDSOLE: 2.5mm bonded felt frost plug OUTSOLE: Handcrafted waterproof vulcanized rubber shell. SOREL? AeroTrac? non-loading outsole. SOREL rated: -40? fahrenheit / -40? Celsius Shaft Height: 8.5 in. Calf Circumference: 15 in. Weight: 27 oz / 765 g. Measurements based on size 2. Imported.