Having a special needs child I am very familiar with cooling vests. The packs can be chilled or frozen, depending upon the need and you don't need to use all of them if they aren't necessary. They are effective, but somewhat bulky and sometimes heavy. The best have tubes through which water flows from a reservoir that can be worn like those water sources bikers use. There are also battery operated vests that have a built in fan turbine which circulates air through a 3D honeycomb mesh. I'm not familiar with how effective they are, but since they are much less expensive, they are probably not as good. Many of our drive-up tms will use battery operated personal fans that they have around their neck on a lanyard.