The Men's Zeus Vest by Marmot. When the thermometer plunges, reach for this ultra light vest, packed with high-quality 800 fill power goose down. It's a great way to stock up on warmth without bulking up your pack, since it fits into its very own pocket! Features include an elastic draw cord hem and cozy hand warmer pockets.
This is the warmest article of clothing I've ever owned, and I love it. Perfect for shoveling snow, or just chilling around the house with. One time I wore this underneath a rain jacket in the middle of a blizzard: stayed toasty warm the whole time. I wear a size small and it's a good fit for me.
So I bought this for my husband who was jealous of my bad ass North Face vest-He loves it-Said it's super warm and he loves the fact that it's super thin(it is) but still warm. He is usually an XL and we bought this in an XL which is large enough to wear his big Moosejaw hoodie undeneath it.