A removable 145g HEAT-MX liner lifts out of the Kamik Nation Plus Boot, a winter boot with a suede upper and 600D nylon detail. HEAT-MX is the brand's thermal insulation, and the boot rates it to -40degF. What Our Gearhead(R) Experts Are Saying:"Shoveling out after a snowstorm, I spent hours in slush, and my feet stayed dry from the first scoop to the last. The fleece lining kept them comfortable even once I stopped moving."