This amazing little neodymium magnet orients North/South so that the cardinal directions can be easily determined (look through the side with the larger hole for South). There are no moving parts to break and it can't be rendered inoperable from being magnetized. It's not only perfect for survival kits, but the hole allows it to be strung though bootlaces, drawstrings, and other out of the way locations. Hang the magnet from a thin string so it can turn unhindered. That all there is to it.