The Patagonia Isthmus Lined Jacket is built for the kind of day that starts cool, warms up on the climb, and turns breezy at the viewpoint. It handles that range as a single layer by pairing a wind-blocking NetPlus shell with zoned warmth: fleece at the torso where the body loses heat fastest, Thermogreen insulation in the sleeves where a shell alone leaves us cold. What Our Gearhead® Experts Are Saying:"The fleece-lined torso is what makes this jacket work as a standalone everyday outdoor layer rather than just a shell. It holds warmth without the stiffness of a full insulated jacket, so it packs flat and moves with me on the trail."