HOLO-KROME 33098 براغي رأس كوب سداسي مقاس 5/16-24 × 5/8 بوصة | سبائك فولاذ معالجة بأكسيد أسود حراري (100 / العبوة)

These set screws came in a heavy-duty bag, not a box, but every single one is cleanly threaded and the black oxide finish is even. I used them to lock a pulley on a motor shaft and the hex drive didn't strip during installation. Exactly the quality I needed for a reliable hold.

The cup point really bites into the shaft once you tighten it down with the hex key, so I’m confident these set screws won’t loosen up during use. Drove them into a tapped hole on a small fixture and the black oxide finish doesn’t show wear so far.

I was a little worried about the hex socket stripping, but these held perfectly under torque for a jig I built. The black oxide finish looks clean and hasn't shown any wear after a few days of use.