I have a cooling scarf and vest from arctic heat. It's bright blue, LOL. Definitely see me coming.

It's not as heavy as some of the others, but it's good for about an hour in the heat. Good for going to festivals for short periods of time. Usually tired from walking around anyways by that point. The biggest problem is that once it stops cooling - it makes one very hot quickly.

The scarf seems to be more helpful than the vest at cooling me down, tho I think it's because I have it right on my skin. Either that, or the back of the neck helps a lot temp wise.

But this is my own experience with it.