Rated to -40° below zero, the Caribou is the timeless choice for cold-weather work and recreation. The nubuck leather upper and handcrafted vulcanized rubber shell are seam-sealed for complete waterproofness and lined with a removable 9mm ThermoPlus™ felt InnerBoot that traps heat next to your foot, where it belongs. Underfoot, a thick rubber midsole insulates the boot from cold ground, while the Sorel AeroTrac™ non-loading outsole provides sure footing.