When we're gearing up for the long ascent up the skin track or a cool fall hike over rolling hills, we throw on the Mountain Hardwear Kor Airshell Warm Jacket for an extra layer of protection. The lightweight jacket features breathable Pertex Quantum Air material and an AirMesh lining that provides light, fleecy warmth. The combination of materials offers incredible temperature regulation, so we can push ourselves further when the weather gets cold.