This little tool was first developed by the US military in 1942 with the purpose of opening K-rations and was later included with C-rations. It’s also known as a “John Wayne” by the US Marine Corps because of it’s toughness and dependability. It’s roughly 1.5 inches long and sports a little folding “tooth” that is what’s used to pierce and cut the can lid. There is also a little hole on the “tooth” end where you may be able to tie some kind of paracord lanyard to it, or at the very least attach it to a key ring.
I was first introduced to this gem of a tool by my Vietnam Vet father years ago, and since it’s been a staple when backpacking and sometimes even around the house. Also, since it’s so small it can fit pretty much anywhere so it’s perfect for an emergency kit or Bug-Out-Bag.
So, if you don’t have one yet go and get one (or three, they’re cheap) but beware of junk imitations! Mine is genuine military issue and is brute tough, I’ve seen some cheap ones just bend on first use.
For more information checkout the Wikipedia page for the P-38 (where I got some of the history and imagery for this post).