براغي رأس مقبس M36-4 × 280 مم | محرك مقبس سداسي | ملولبة جزئيًا | فئة 12.9 فولاذ سبائكي أكسيد أسود حراري

The 12.9 alloy steel grade gives me confidence these will handle heavy clamping loads in my press jig without stripping. The black oxide coating also seems consistent and durable across all four screws I ordered.

The hex socket drive bit right in without any wobble, and the 12.9 alloy steel feels seriously solid for a 280mm screw this size. I’ve used cheaper bolts that stripped on installation, but these threaded cleanly into my jig setup.

The partially threaded design made these bolts much easier to align in my press jig than fully threaded ones would have been. The hex socket drive gave a solid grip with no slipping during torquing.