I thought I did a review on this product, but I didn't see one in a search.
Last year I bought a Ridecool vest as I was tired of getting so dehydrated on long trips. It was a revelation, literally making me too cold if the temp was below 30.
Here's a link: http://ridecool.com/catalog/index.ph...470a9752ed63cc
I got the Deluxe Cool riding vest, but probably would have sprung for the cheaper Sport Cool vest as the collar on the Delux Cool is a pit bulky. That said, the deluxe probably cools a bit better than the sport.