There's layers to this. From the outside in, Chamonix's outer shell features densely woven recycled PET with water-resistant properties. Beneath the surface, a layer of soft microfleece blankets recycled polyester insulation for maximum warmth when temperatures begin to dip below zero. Glacierguard™ technology acts as a thermal barrier to trap and retain heat under your toes, while shielding out the cold front.