I work at a Northern Tier oil refinery and this bad boy is keeping me nice and toasty...
It's big enough that you can wear several layers underneath and it is warm enough that anything over 40 degrees is going to be too hot for it.
I'm a diehard Carhartt fan (1 own 13 coats and jackets) so I when I brag on this one, I know what I'm talking about.
It's FR4, so it can be worn at any facility which requires FRC clothing.
Great buy at a great price!