HOLO-KROME 73100 براغي رأس مقبس 3/8-24 × 5/8" | محرك مقبس سداسي | فولاذ سبائكي معالجة حرارياً بأكسيد أسود (100 / عبوة)

Installed these on a milling fixture and the black oxide coating held up better than I expected against chips and coolant. The threads were clean and consistent across all 100 pieces.

The hex drive seated perfectly on my Allen wrench with zero wobble, and the thermal black oxide finish has held up through a week of assembly work on my jig without a hint of rust. These are exactly what I needed for precision tooling.

I was a little skeptical about the black oxide finish holding up, but after using a few in a precision assembly, the coating hasn't chipped and the socket drive fits my hex key perfectly.