Thread: Underrated but Valuable Kit

I've signed up to become a LandSAR trainee now and I've been adding some extra gear to my kit after studying some bushcraft and rescue manuals...

I've noticed the more I learn about what goes wrong and how to prepare to prevent it in New Zealand bush, the more pieces of kit I often overlook seem more and more valuable.

For example; Hypothermia is our country's number one killer of people in the bush (thanks to our 4 season, all-year-round weather changes). We're told to pack things like a survival blanket, sleeping bag, bivy bag/tent/fly etc. But never once, ever, has someone told me to pack a thermometer? Considering that one of the most important symptoms and best way to monitor if someone is deteriorating is to monitor their temperature. Yes there are always the outwardly signs but often these are when people are on the move when you see them. If someone's core temperature drops below 35 degrees to 34, 33, 32 etc they're in danger. Also, although the symptoms are a sure sign - there are likely many times they are not very evident.

A thermometer is a $10 piece of kit and weighs less than a toothbrush. It would help me assess someone's condition, and my own, a lot more thoroughly. Also not just for hypothermia but if someone caught a bug or a fever as well.

Another one I can think of is a life-straw, although I have a filtered waterbottle, rather than carrying aquatabs etc. Things that make the difference for preparation.
I've also considered for an extra emergency food pack to get an MRE that heats itself. Just one pack for a long trip on top of my other food, because even with a PLB you can still get in a situation where you won't be rescued for awhile, but too injured or unable to cook up something hot yourself. They are just $20.

What other pieces of kit have people found incredibly useful, that are not on the common list of "what to take into the bush"? Not necessarily high-tech either. Would like to know and get a thread going.