Spring Pin, M4x20

The rolled pin seated cleanly into my jig’s 4mm bore with a firm tap, and the 20mm length gave just enough engagement for a solid hold. It’s stayed put through a few vibration-heavy milling passes, no wobble at all.

M4x20 is exactly the right size for aligning jig plates on the mill, and the rolled ends slide in cleanly without catching. Held up through a few dozen test fits without any burrs or deformation. Solid little pins for the price.

I needed a 4mm pin for my lathe project, and this M4x20 spring pin fit the pilot hole perfectly without any filing. The 20mm length was exactly what my jig required, and it holds securely in the steel block.