True to size for today's "athletic fit" clothing like Nike Pro, UA's running stuff, etc. Construction quality(stitching, neck, cuffs) is not on par with those, but neither is the price, and it's not bad. VERY pleased with the performance. Cool in the heat, dries very quickly. Odor control/anti-microbial treatment is good for several uses, at least initially. Bought 7 for work, but kept one aside for testing-30min of Cybex Arc Trainer at the gym, yard work at 95F and an ~15 mile overnight hike with daytime temps in the upper 80s over the course of a week, and between washings. Getting a little musty after that last, but a very good showing, overall. I work out in the elements, and am an avid outdoorsman. Have a pretty huge variety of synthetic baselayers/tops, from budget offerings to the aforementioned Nike and UA, along with lots of Patagonia Capilene in 3 different weights. *For the price*, I think this is as good as it gets in a lightweight top for warm weather. Construction aside, I have no real preference for any of my "premium" shirts over these for regular use. 5 stars for value. More than satisfied. Wash before wearing, no dyes, scents or fabric softeners, hang dry preferred.