I have a crocheted qiviut hood given to me by a friend who used to live in Alaska. She gave it to me when she moved from Alaska to Florida. Being crocheted, it has lots of holes, but it is INCREDIBLY WARM. I love it but have little use for it in our recently milder winters. It is also incredibly soft, even softer than cashmere. If yak wool is that warm, I may pass on the Eileen Fisher sweaters.