The vests definitely stay cool, and for an impressive amount of time too! (Ive heard up to a week!) They look pretty decent and don't make you stand out too much while wearing them which is definitely something I appreciate. I feel the sizing for the large definitely runs much larger on the "adjustable" vests which are a bit more expensive by comparison. Because of this, the two vests I got don't seem to fit to my body as closely as I'd hoped (having not been able to try one on) which really limits the amount of cooling contact to my body. I plan on altering the elastic by sewing it a bit tighter to reduce the amount of material depth wise. Additionally my last qualm was that, the black vests do seem to leech out a bit of the dye onto clothing over time, especially when freshly hydrated, and can leave contacted surfaces feeling a bit ...soapy, perhaps? I'd simply warn against wearing anything under the dyed vests you don't plan on getting marked up into a checkered pattern. As far as I understand these vests seem a bit difficult to run clean of loose dye before use due to their absorbancy and nature of use outside of considerable soaking over time. Great product, just would have liked to see a bit more forewarning of fitting and leeching concerns, but admittedly I bought in person at a trade show. User experience may vary. Would recommend for sure as far as their designated purpose. I even gifted one to my father who the large fit much better due to his huskier and larger bellied stature (about 5'8" 180-190lbs). Thin, flat bellied guys should likely go for a medium to account for a more tight fit. However, Im a little unsure yet of how the gel pads hold up to hard labor. They seem a little delicate and I'm wary of bursting them under weight like a heavy board or crawling under a house.