I work outside all the time summer and winter have been for about 25 yrs I have bought just about every type of thermal base layer (long johns) some worked ok some were junk. I came across the David Archy fleece base layer. I figured I would give them a shot. Well to my surprise these things are Phenomenal They fit like a glove in there so comfortable I was in for 2 days straight They kept me very warm If you come across these and do not buy them it will be a mistake on your part