براغي رأس أسطواني M4-0.7 X 40mm | سداسي داخلي | جزئي الخيط | درجة 12.9 سبيكة فولاذ مؤكسد أسود حراري (400/عبوة)

I was surprised by how well the black oxide finish held up during assembly — no scratches even after tightening with a hex key. The partially threaded design made them perfect for securing brackets on my jig without bottoming out.

The hex socket drive on these M4 screws engaged perfectly with my Allen key—no stripping or wobble. The black oxide finish has a nice, even look, and the 40mm length is spot-on for my jig build.

The partially threaded design gives a solid bite for jig adjustments, and the black oxide finish on these screws has held up well in my machinery setup. I’ve used a full box on tooling projects without a single stripped head.