Baffins Polar Proven? specialized boots are rated to perform at-100?C/-148?F. Tested at both the North and South Poles, these boots perform flawlessly under the most demanding conditions. In our Polar liners we doubled up on B-TekTM insulation and added a double aluminum insole and waffle-comb foot-bed to trap the warm air produced by your body and keep the cold out. This series is appropriate for extended periods of time in extreme cold weather, snow and/or ice covered environments, where activity level may be low to moderate.