Warmth, comfort and versatility. Incredibly adaptable, these items can be used as either a mid-layer or as an outer layer. We use Polartec® Power Stretch® Pro™ and our own synthetic insulation. Polartec® Power Stretch® Pro™ is engineered to push the performance of stretch fabrics by keeping you warm and dry through touch points that diffuse and evaporate vapor moisture in the outer layer. Reinforced elastic fibers ensure the fabric consistently rebounds after every stretch. This next-to-skin layer stays dry, breathable and comfortable by continuously transferring moisture vapor for rapid evaporation.