An insulation breakthrough: the new Nano-Air™ Vest featuring FullRange™ Insulation is warm, stretchy and so breathable, you can wear it for the entirety of any highly aerobic start-stop mission in the mountains. Both shell and lining with mechanical stretch and a DWR (durable water repellent) finish. Insulation: 60-g FullRange™ 100% polyester stretch insulation Icy runnels up high, sun-warmed rock down low. Whatever your preferred medium, core warmth matters, and Patagonia's new Nano-Air™ Vest keeps pace throughout high-output, stop-and-go missions in variable conditions.