The Patagonia Nano Air Light Vest is a very light and breathable insulating gillet, made to be worn for the entirety of your aerobic, start-stop mountain activities, so you're never slowed down by having to change layers. Stretchy and breathable FullRange insulation dumps excess heat when you're working hard and keeps you warm when you're not. The insulation is Patagonia's own 40-gram FullRange, which is 100% polyester (93% recycled) insulation delivering outstanding warmth, mechanical stretch and air permeability (35 CFM), allowing excess heat to move away from the body. There are two handwarmer pockets and one left-chest pocket that's zippered, low profile and low bulk to wear comfortably with a harness or a pack; self-stuffs into the chest pocket. Patagonia Nano Air Light Vest Features Synthetic 40g FullRange insulation 87% recycled Polyester shell DWR finish Four way mechanical stretch 1 external zipped left chest pocket 2 zipped hand warmer pockets Dual adjustable drawcord hem Weight:211g Patagonia Nano Air Light Vest