HOLO-KROME 72184 3/8-16 X 5" 內六角螺絲 | 六角驅動 | 合金鋼 熱處理黑氧化物 (50 個/包)

The threads chased perfectly clean on my mill table T-slots, and the black oxide finish held up without any flaking during tightening. Fifty pieces for this price is a solid deal when you're burning through fasteners on a fixture build.

I used these on a press jig I'm building and the black oxide finish went on smoothly without binding. The 5-inch length was exactly what I needed for the thicker plate stack. Very consistent threads.

Finally, a socket cap screw that doesn't strip on the second tighten—the hex drive bites perfectly every time on my jig builds. The thermal black oxide finish has held up through a week of oily shop use without a speck of rust.