HOLO-KROME 72330 3/4-10 X 6" ソケットキャップスクリュー | 六角ソケットドライブ | 合金鋼 熱処理黒色酸化被膜 (10本/袋)

I’ve been using these on a heavy-duty jig I’m building, and the black oxide coating gives them a nice, even finish without any burrs. They seated smoothly into the threads and held up well under torque.

These hex screws tightened perfectly on my milling machine jig, and the black oxide finish already seems tougher than standard zinc plating. For the price of a 10-pack this size, they’re a solid value if you need serious holding power.

These hold like nothing else I've used on my jigs—the black oxide finish makes them slide into tapped holes without any galling. The socket drive bites cleanly with an Allen key, and all ten came out of the pack with perfectly clean threads.