I have a Miracool vest and like it a lot so far. After it is charged with water (20 minute soak) is holds water a lot long than my vest from Cycle Gear. My Cycle Gear vest only last about 30 minutes on the freeway on 90+ degree heat. The miracool will last for hours. The mira cool is heavy when fully charged with water and I do look like a highway worker with my bright orange vest but it is well worth it. I took mine on our ride to camp outing this weekend and it lasted the entire weekend which was probably around 8 hours riding time over two days. It is holding water sitting in my garage.
I have a slightly used Cycle Gear vest for sale now.
Now if I can just figure out how to get a pair of Mira Cool underwear.