This shirt is a life saver. I've struggled with sweating ever since I can remember. It got to the point I was bringing a spare under shirt and spare button down to work almost everyday. If I had a meeting or presentation I was always changing shirts before or after. I own two of every dress shirt just so that people won't notice if I change my shirt mid day at lunch due to sweating.Gone are those days. I just spent a week on the road, meeting with customers, execs, teaching classes, all sorts of things that up my anxiety and make me go through shirts. This shirt really is sweat proof. I did the unthinkable. I wore the same shirt on a 16hr day. Never in my wildest dreams did I think I'd be able to do that.These shirts have changed my life, I'm more confident, comfortable, and not worrying about my sweat all the time.Side perk, if you buy them a tad small, they can help keep your belly in. :)I ordered the small, and it works great. Good length to tuck in, nice and tight in the pits so that nothing transfers to the overshirt.Worth the price alone just to keep from ruining dress shirts with permanent pit stains, let alone laundry/dry cleaning bills. But honestly, the confidence and freedom from worrying is priceless. I own 5 shirts now, one for each work day.