What’s the most underrated tool in your machine shop?

Every shop seems to have that one tool that doesn’t get much attention but somehow ends up being used all the time.

It might be a simple deburring tool, a good set of parallels, a magnetic base, a depth gauge, a quality file, or something completely unexpected. Not necessarily the most expensive tool in the shop, just the one that quietly saves time, fixes annoying problems, or makes everyday work easier.

What’s the most underrated tool in your machine shop, and why do you think more people should be using it?