براغي رأس مقبس 1-3/8-6 × 5-1/2" | قيادة مقبس سداسي | ملولبة جزئيًا | فولاذ سبائكي بأكسيد حراري أسود

For a 5-1/2-inch partially threaded screw, the thread engagement up top is spot-on for clamping thick plates without bottoming out. The hex socket drive bit seated firmly, and the black oxide finish looks uniform across all ten I ordered. Just torqued them into a jig fixture and they held rock solid

The black oxide finish is holding up perfectly on my jig build, and the hex socket drive made installation effortless. These are exactly the right size for my press tooling.

Put these on a custom milling fixture and the hex socket drive made installation in a tight spot much easier than a standard bolt would have. The black oxide finish seems durable so far.