Nut, M8 Nylon Insert Lock

Used these on the handwheels of my bench mill and they haven't budged through a week of steady use, even with vibration. The nylon collar seats smoothly without needing a lot of force to get started. Just wish the pack came with a couple extras for spares.

Used a handful of these to secure a handwheel on my mini lathe and the nylon insert locked it down firmly with no wobble. Much simpler than messing with a separate lock washer.

The nylon insert really grips the bolt threads tightly, so my handwheel stays put even under vibration during machining. It threaded on smoothly with no binding, which was a nice surprise.