What Our Gearhead(R) Experts Are Saying: "This is one of my favorite layers for high-output days. It blocks wind incredibly well without overheating, dries fast after hard climbs, and layers cleanly under a shell when conditions turn. I reach for it constantly for trail runs, fast hikes, and scrambles." We rely on the Aerotherm Jacket when the day calls for speed, movement, and adaptability. Built by Mountain Equipment for fast-paced mountain travel, this lightweight layer balances wind protection, breathability, and just enough warmth to stay comfortable through variable conditions. The windproof EXOLITE 45 outer fabric cuts exposure on ridgelines while remaining flexible and breathable during sustained efforts. Inside, a soft micro-grid lining actively wicks moisture and adds light insulation, keeping us dry and comfortable through stop-start movement. Finished with an active fit, adjustable Mountain Hood, and a highly packable design, this jacket is one we keep close anytime the forecast looks uncertain but the pace stays high.