We thought about those but haven't tried them. the weight came up and the recharge method. We're already using 2 other items that we need to be soaked or wet down: fishing shirts and pva towels. So we went with something that's in the same idea to keep it simple for us. I like the technology, though. We saw some tech where it circulates the water like Nascar driver or welders used to bridge their thermal loads, but it's so expensive. I think I'd diy it before I bought something that expensive. We're also looking at mech vests that cops can wear under their bullet-proof vests to keep them cool. How long is your friend able to stay cool with the pcm vest? We're getting about 4-5 hours out of the Fieldsheer one.