Merrell Men's Norsehund Beta 8" Waterproof Suede 400g Merrell Opti-Warm lightweight, low-bulk, synthetic insulation keeps you warm in varying conditions 300g Merrell Conductor Fleece provides lightweight, versatile heat retention in varying conditions ColdSmart Thermal System regulates your temperature with airflow channels keeping your feet dry and warm 5.5 mm sole lug dept Comfort Range to -40F