We’re big fans of the trend towards base layer and insulating garments that are both loftier (more insulating) and more breathable (less dense knit). This extends their comfort ranges across a wider variety of temperatures. Worn alone, their open knit structure doesn’t result in overheating and allows moisture to pass, but when used as a base layer under a shell or other layers, the loft and air pockets trap body heat to keep you warm. The Senchi Designs Waxwing Hoodie works like this. It’s made with Polartec Alpha, which is a fabric that’s rarely used on its own in garments due to its lack of durability. However, in this situation, it’s an incredibly innovative use that results in a dramatic warmth:weight ratio and a garment that weighs only 4 oz! For experienced hikers only – know the durability limits of this type of insulation, and how to use it most effectively in concert with your other layers.