This is the piece for the woman who demands performance, durability, and flexibility in her midlayers. The Arc'teryx Proton Women's Hoody was built for alpine and rock climbing, high energy output in cold weather. This is an extremely durable face fabric that’s extremely air permeable, allowing moisture and excess heat to escape easily. The Fortius™ Air 20 face fabric has unrivaled hardwearing durability, over 60 times more durable in abrasion tests than the industry standard for a jacket you can confidently wear on its own, or, of course, under a shell. Coreloft™ Compact 80 synthetic insulation in the body maintains excellent stretch and compression recovery, as well as allowing humidity to pass through it. Need more venting? The No Slip Zip™ stays where you put it.. up to your chin, to your mid-chest, or lower, without shifting, so you can stay forcused on what you’re doing, not what you’re wearing. Top this off with the helmet compatible insulated hood for really chill weather and you’ve got a great piece for winter cold insulation right through chilly summer summits with a low profile fit for easy layering.