براغي رأس تجويفي HOLO-KROME 76543 مقاس M20-2.5 × 200 مم | محرك تجويف سداسي | فولاذ سبائكي مؤكسد أسود حراريًا (10/عبوة)

Threaded these right into a precision jig I’m building, and the black oxide finish didn’t flake off like cheaper coatings I’ve used. The hex socket grabbed the driver cleanly every time.

Had to really torque these down for a jig assembly, and the hex drive held perfectly without stripping. The black oxide finish looks and feels tough, and the threading was clean on every single screw out of the ten-pack.

Used these on a heavy-duty fixture at work, and the black oxide finish held up well against minor abrasion during assembly. The hex socket drive engaged cleanly with my driver, no stripping on the first ten screws.