Stephen Cline wrote a review of The North Face ThermoBall Insulated Vest - Men's on March 16, 2017
Grabbed one of these to bolster my layering system and couldn't be happier. I like the fact that I can add it under my wind shell or hardshell and still have plenty of room in the arms of my jackets. Have used it down to about 18° F with a long sleeve powerwool base layer and BD coefficient fleece (very light fleece) and was plenty comfy when static (no wind). I'm impressed with the NF thermoball insulation.
Got the medium (5'"9", 175 ish) and fits well. Plenty of room for layers under and can easily get a shell over it.