My husband usually wears the Under Armour 4.0 base layer shirts which he absolutely loves working outside in cold temps but they are very expensive. I read all the great reviews about Go Athletic apparel and decided to see if was the same since, according to the reviews, it was comparable, less pricey and made in the USA. It's heavier and seems to be of the same quality. He hasn't worn it yet in cold/arctic weather yet but I think it's a very comparable option to the more expensive brands. For reference he's 5' 8" and 185 lbs and the large fits him. Thank you for all the helpful reviews!