Sorel Caribou at Alamo Shoes in Chicago . . . 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 wet winter weather. Upper: Waterproof nubuck leather upper. Seam sealed waterproof onstruction. Insulation: Removable 9mm washable recycled felt inner boot with Sherpa Pile snow cuff. Midsole: 2.5 mm bonded felt frost plug. Outsole: Handcrafted waterproof vulcanized rubber shell with Sorel aero-trac non loading outsole.