براغي ذات رأس أسطواني M30-3.5 X 190mm | محرك سداسي | خيط جزئي | فئة 12.9 فولاذ سبائكي أكسيد أسود حراري

I’ve used a lot of 12.9 alloy steel fasteners, but the black oxide finish on this one feels properly durable—no flaking even after torquing it down in a jig. The partially threaded length gave me just the right grip for a heavy clamp setup.

The black oxide finish on these screws held up perfectly against the tight tolerances in my jig setup. The hex socket drive made installation straightforward with no cam-out issues.

Installed these in a large press fixture I've been building, and the 190mm length was exactly what I needed to bridge the main mounting plate. The black oxide finish handled a few light oil sprays without any sign of corrosion during the trial run.