Sorel Caribou Snow Boots 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, wet winter weather. Product Features Upper: Waterproof nubuck upper. Seam-sealed waterproof construction; Insulation: Removable 9mm washable recycled felt inner boot with Sherpa pile snow cuff; Midsole: 2.5mm bonded felt plug; Outsole: Hand-made waterproof vulcanized rubber shell with Sorel aero-trac no-load outsole; --