I baught this thinking it was a semi-light jacket, that had some sort of lining. I is not lined at all. The material is roughly as thick as a heavy t-shirt. It is warmer than a t-shirt, but if its lower than the mid 40s or so, this won't be enough jacket. In short, if its cool enough to need a jacket, this one is a bit too thin. Im not sure exactly what the application for this would be. That said, it seems very well made, and looks nice. Be aware though that the size runs large, so if your on the line, go down rather than up. In fact, had I not already had to exchange this for a smaller size I would return it, and get a different jacket. This is just not what I was looking for. Its nicely made, though, so if your tougher to the cold than I am, it may be what you want.