I received this yesterday and just gave it a test drive. The challenge: mowing the front yard. Conditions: north central Florida, air temp 86F, feels-like temp 91F, started at 7:00pm, finished at 7:40pm. Usually my shirt would be soaked with sweat but not this time - my shirt was dry! Was I cool as a cucumber? No, but I also didn't feel like I was gonna die. Did the vest keep me cooler? Yes! Did it puff up like the Michelin man and look a little silly? Also yes but a small price to pay for avoiding heatstroke. For the record, I had it on the lowest setting (1) while mowing and the battery only dropped to 98% after running for 40 minutes. Just for fun I turned it up to 3 afterward and it was super breezy - I'm pretty sure if I bumped it up to 5 I could have gotten airborne (hence "to the moon!). I do wish it came in larger sizes; I'd like to get one for my cousin (he works construction) but don't think an XL would fit him. For the record, I'm a 5'7" old(ish) lady and usually wear a size 14/L except for Columbia gear (XL). I think this vest will help me to survive another brutal Florida summer!