Others have mentioned, but note that this is mostly a nylon windbreaker. There is a small amount of wool under the arms and around some of the back. If you look at the gray, the "wool" is the black portion. It appears that the wool is for fashion and not function. For a nylon vest that is fashionable, I simply cannot invest this much coin - back it goes.

This vest is completely useless. I didn’t get into the fine print and thought I got a good deal from a good company in Smartwool. This is actually a single layer of plastic with a couple vents, as if someone took my ultralight rain jacket and sewed the pockets shut, cut off the sleeves and hood then cut a hole in the back.

No product has ever been more disappointing.

Genuinely, I can’t imagine what purpose this serves.

It’s so useless I can’t even give it to the dog.

Nice wind breaker material but thinner than what I wanted. I was looking for a base layer weight vest and ended up going with this one: https://www.backcountry.com/icebreaker-tech-trainer-hybrid-vest-mens#wall-solicitations