I have this shirt – 4.0. I got it for about $30 from TJ Max, and I love it. It has a thin soft fleece lining, sleeves are designed really well. Cuffs look a little weird with a extension in thin material that sticks out (you can tuck it in under the cuff), but it’s functional in being close but not tight on the wrist and allowing it to extend up the hand to use the thumb hole.
It does a great job holding in heat when it’s cold but also venting when I’m hot. I pretty much live in it all winter in the house, winter run/hike in it, and take it as my sleep top/long-sleeve layer for summer backpacking. Down to about high 30’s, I am very comfortable active in just the Terramar, a windshirt, warm hat and gloves. Low 30’s or below freezing, I need a 100wt fleece to not feel cold but then it’s harder to avoid overheating.
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