M5-0.8×30mm キャップスクリュー | 皿頭六角穴付きドライブ | 全ねじ | 12.9級合金鋼 熱処理黒色酸化被膜（400個/袋）

The black oxide finish on these screws is much more consistent than the silvery ones I used before, and the hex drive grips perfectly without stripping. They seated flush into my jig frame without any wobble, and the 12.9 grade steel feels solid enough for production tooling.

Had to swap out some cheap machine screws on a fixture, and these flat heads sit flush without any wobble. The black oxide finish looks clean and professional, and the hex drive made installation quick with no stripped heads. Exactly what I needed for precision tooling work.

These worked perfectly for the jig I'm building; the black oxide finish is slick and uniform across all 400 pieces. I was a bit surprised at how well the hex socket grips the driver—no cam-out on the first few test fastenings.