Rated to -40 below zero, the Caribou Wool is an ideal choice for cold-weather work & recreation. The full-grain leather upper & handcrafted vulcanized rubber shell are seam-sealed for complete waterproofness & lined with a removable 9mm felted wool Inner Boot that offers unparalleled natural insulation. Underfoot, a thick rubber midsole insulates the boot from cold ground, while the Sorel Aero Trac non-loading outsole provides sure footing.