Neck Coolers: If you think your son/daughter will use a neck cooler on the trek then you may also make or send one with them. You can purchase them on Amazon or at Deseret Book.
Neck Coolers are also easy to make. There are many options on Pinterest or you can go to this blog for instructions.
They are a great way to stay cool in the heat.
There are also cooling towels that once they are wet have a cooling technology that can be activated by snapping the towel. They can be purchased at Costco, Big 5 or Amazon.
The reason they are a good idea is that one of the bigger concerns on trek in July is the heat. The neck coolers and towels will help keep trekkers cool.