The Kamik Men's Nationplus Boots offer rugged and flexible protection that holds up to the toughestconditions. Waterproof, warm, and lightweight, these hardworking boots will weather the toughest storms. Seam sealed waterproof construction and injected synthetic rubber shell, specially treated andsealant-taped to keep feet dry no matter what. Moisture-wicking lining with 200g Thinsulate and foamremovable liner are comfort rated to -40F/-40C by the PTC (Performance Testing Council). A unique microfiber developed by 3M Thinsulate insulation is constructed of unique fibers that trap air, retain body heat, and deliver warmth.