Here's my initial review on the cooling vest. For my first use I was wearing a polyester underarmor type shirt and I wore the vest underneath my mesh high viz vest.
I purchased my cooling vest at my local Cycle Gear. It's their Bilt brand and it was about $35.00. It fit true to size and it was cut short in the front to prevent it from bunching while on the bike. The material, while dry, feels and looks a lot like a quilt.
I followed the directions on use by submerging the vest in water for a minute or two and then pat it dry so it isn't dripping wet. I suppose you could leave it as wet as you want depending on how wet you mind getting.
I put the vest on before I left work. I instantly felt cooler but I also could tell it would only be a minute or so before I also felt wet. Once I hit the road there was a clear difference in the way I felt. The vest really did make it more comfortable to ride in the 100+ heat provided you don't mind getting wet.
The vest took a very long time to dry even though I let it dry outside where it was nice and hot. I'd say the total dry time was nearly 10 hours. I suspect that it would stay wet for at least a few hours if your were actively driving in such heat.
Once the vest was totally dry, the material became somewhat stiff. It's not hard to fold to put back into my side case but it doesn't retain it's shape while folded.
Overall, I think it's a worthwhile addition to my riding gear although it's not really worth using on a short ride. If these were $50.00, I would do without.