M30-3.5 x 400mm 內六角螺絲 | 六角驅動 | 部分螺紋 | 12.9級合金鋼熱處理黑色氧化

Needed a high-strength bolt for a press fixture, and the Class 12.9 rating on these means they handle the load without any issue. The black oxide finish looks professional and seems to resist minor corrosion so far.

The partial threading on these M30 screws makes alignment in jigs much faster than fully threaded bolts I've used before. They torqued down evenly on my press fixture and the hex socket held up without any rounding. Solid hardware for heavy assembly work.

The black oxide finish looks properly done and the threads are clean all the way down. I used these for a heavy jig setup and the 12.9 alloy steel feels rock solid, no flex at all under load.