M20-2.5 X 40mm 內六角螺絲 | 平頭內六角驅動 | 全螺紋 | 12.9級合金鋼 熱處理黑色氧化 (25 個/包)

The thermal black oxide finish looks properly done, no patchy spots, and the hex socket drive grabbed cleanly without stripping. Fit my jig fixture perfectly and the 12.9 alloy steel feels rigid when torqued down, so I’m confident these will hold up in daily use.

These M20 cap screws tightened down with satisfying precision in my jig build, and the hex socket drive held up perfectly under torque. The class 12.9 alloy steel feels reassuringly robust for heavy-duty use.

The black oxide finish on these screws is holding up great on my jig setup, no rust after a week of use. They threaded perfectly into my M20-2.5 tapped holes without any binding. Exactly what I needed for a solid, heavy-duty assembly.