Review on MC-0M011060 Pin with Negative Tolerance by Mike Marks

I bought these to make sure the holes drilled in circuit boards are the correct diameter (board manufacturers often change the drill sizes from your specifications and won't tell you about it). The pins are precision ground to approximately 5 ten-thousandths undersize based on micrometer sampling, making them perfect for "continuity" hole testing. They're actually coated in light machine oil, and while I'm not sure the specific alloy used is fairly bend resistant, so it's probably some sort of tool steel. The recesses where the pins sit appear to be slightly magnetized when they are sit vertically, although the holes are slightly larger in diameter, but the magnetic attraction isn't strong enough to hold it when you knock the box over.