SAW STYLE BROKEN KEY EXTRACTOR, A MUST FOR EVERY LOCKSMITH'S TOOLBOX
If you work on vehicles, you get fairly frequent calls to remove keys broken off in door or ignition locks. This happens with household and commercial door locks, too, but not as frequently. Broken key extractors are literally required to service these jobs, and one of the most basic type extractors is the sawtooth. These tools are extremely effective in many cases, used to work into the keyway and hopefully catch on the teeth of the key.
The EZ-1 from HPC is a basic, reliable extractor with a low enough price that it makes sense to have 2-3 extras on hand. They do break (all key extractors are prone to breakage for obvious reasons), and getting caught without one of these can be infuriating.