High-performance inForm Tundra last has a snug fit; we suggest sizing up for optimal warmth and comfort;The Vibram rubber outsole provides sure-footed traction and long-wearing durability;Boa System allows precise fit adjustments even while wearing heavy gloves;Removable, felt-lined neoprene inner bootie provides enhanced insulation to retain warmth;Durable upper with waterproof membrane keeps feet warm and dry;GnarGuard rubberised toe and heel bumpers protect against abrasions and fight debris;