Nano-Air has been such a success for both Patagonia and alpinists that Patagonia finally produced the Men's Nano-Air Insulated Pant for serious alpine endeavors that require extra warmth and air-permeable performance. Unlike standard breathable garments that only breathe until after you start sweating, the Nano-Air's air permeable insulation allows the pant to breathe the moment you put it on. The exterior fabric is just as breathable, and it's soft enough to wear around cold campsites, yurts, and basecamps. Patagonia treated it with DWR to shed light moisture from falling snow and moisture-riddled tents.