What Our Gearhead® Experts Are Saying:“This is my go-to fleece for climbing, ski tours, and cold-weather hikes. It’s warm but not bulky, and I love how the Polartec Power Stretch Pro breathes and moves. It layers cleanly under a shell or works great on its own for casual days.”We reach for the Aconcagua ML Hooded Jacket when our days call for dynamic movement in cold conditions. Built with trusted Polartec® Power Stretch® Pro™, this midlayer blends warmth and moisture management in a sleek, abrasion-resistant package that doesn’t bulk out our layering system. It’s warm without being stuffy, with the quick-drying and breathable performance we count on for climbing approaches, skin tracks, and blustery ridgelines. Mammut’s thoughtful design comes through in the details: a helmet-compatible fitted hood, thumb loops that layer seamlessly under gloves, and a slim athletic fit that moves like a second skin. Two backpack-friendly zip pockets give us storage without interfering with harnesses or hip belts. Whether we’re heading into the alpine or just staying cozy in camp, this piece always earns its spot.