Irish Setter® by Red Wing Shoes® IceTrek Winter Hunting Boots are the ultimate extreme-cold Boots for late-season hunters, ice anglers, snowmobilers, and anybody else who doesn't let the cold keep them inside. 1,600-gram PrimaLoft insulation along with innovative ThermalBoost technology delivers extreme warmth without the bulkiness usually associated with heavily insulated boots. The difference-maker is ThermalBoost, a revolutionary, multi-zone insulating technology that adds the equivalent of 400 grams of additional insulation without adding bulk or weight. This extra insulation is applied strategically to the specific zones of your feet that are most prone to heat loss: the toe box, beneath the insole, and within the footbed. That means your feet and toes stay warmer, longer—even in extreme cold.