HOLO-KROME 32156 5/16-18 X 1-1/4" Binnenzeskant Stelschroeven met Kompunt | Gelegeerd Staal Thermisch Zwartgeoxideerd (100 / Verpakking)

The hex socket drive seats the Allen key perfectly with zero wobble, and the black oxide finish has held up well under repeated tightening. I've used almost the whole box for locking pulleys on a conveyor line, and every one has stayed put through a week of heavy vibration.

Got these to replace some worn set screws on a milling machine clamp, and the black oxide finish looks much cleaner than the plain steel ones I had before. The hex socket drove smoothly without stripping, and the cup point bit into the shaft firmly with just a few turns.

These fit perfectly into my shaft collars and the black oxide finish makes them much more durable than the plain steel ones I used before. The hex socket drove in smoothly with no stripping.