Often imitated but never equaled, Sorel's Caribou is the true icon with a nubuck leather upper, waterproof seam sealed construction, and a removable felt inner boot for warmth, comfort, and protection in cold, wet winter weather.. . . . Sorel comfort rated to 40AdegFC for extreme warmth. Removable, insulating 9 mm washable felt inner boot with two layer construction:. Polypropylene and recycled polyester wick moisture and trap warm air. Reinforced seams and heel area for exceptional durability. Stretch front shaft ensures comfortable fit and seals cold air out. Sherpa Pile snow cuff to keep snow out. Aero Trac rubber outsole and nonloading lugs for sure footed, slip resistant traction on snow and ice. 2.5 mm bonded felt frost plug midsole increases thermal barrier between your feet and cold ground. Seam sealed waterproof construction. Waterproof nubuck leather upper for protection and durability. Handcrafted, waterproof, vulcanized rubber shell to keep feet dry. Shaft height: 10 in. 25.4 cm.