Can always carry one of these. If I ever go to Moab in July again (lol doubtful) I am for sure taking one. Our group needed to do some pretty intensive electrical troubleshooting & repairs on a jeep in the middle of Where Eagles Dare and for an hour and a half everyone just baked. One of these...
I like these when someone that has a big brain explains these kinds of things. Eric Weinstein is great at explaining complicated concepts.
I have to read these a couple times and even then I don't always grasp it