This is the warmest Muck Boot made, and a popular choice for Antarctic station workers, Alaskan hunters and Canadian ice fishermen. The Arctic Pro is tailor-made for extreme conditions, with 8mm of CR Flex-foam, a toasty fleece lining and 2mm of insulating foam underneath the footbed. The flexible topline hugs your calf to keep snow and freezing air out while preserving existing warmth. Boasting an EVA molded insole and super-aggressive Bob-Tracker outsole.