M36-4 x 220mm 內六角螺絲 | 六角驅動 | 部分螺紋 | 12.9級合金鋼熱處理黑氧化

The black oxide finish on these screws looks really professional and seems durable. They threaded smoothly into the mounting holes on my press fixture with no binding at all. Perfect fit for the heavy-duty tooling I'm building.

Installing these in a heavy-duty jig was a breeze—the hex socket drive grabbed perfectly without any stripping. The black oxide finish looks clean and professional, and the partial threading gave me exactly the grip length I needed for my tooling setup.

The 12.9 alloy steel is the real deal—these screws held up perfectly under heavy torque in my jig setup, and the black oxide finish gives them a nice, uniform grip. Threading was smooth all the way down, no binding at all. Exactly what I expected for precision work.