Originally Posted by lubbockhammockguy
I know that the Columbia Omni-Heat base layer is breathable and heat reflective.
In my practical experience with it (I have a fleece with it), I've found it to be very warm for the weight, but not as breathable as "regular" fleece wear.
I guess that's to be expected. But it does seem to act as a vapor barrier of sorts, so if I work up a sweat, I stay pretty sweaty.