HOLO-KROME 86646 5/16-18 X 4인치 소켓 캡 나사 | 육각 드라이브 | 합금강 열처리 블랙 옥사이드 (50개/팩)

The black oxide finish on these screws gives them a nice, uniform look, and the hex socket drive grabbed my Allen key perfectly without any stripping. I used about thirty of them on a steel jig and the threads cut cleanly all the way in. Solid fasteners for the price.

Threaded all fifty into a fixture plate this afternoon without a single stripped drive—the black oxide coating lets them seat smoothly and the 4" length gave plenty of grip for the base plate. They feel solid under a torque wrench, no wobble or flex.

Bought these for a jig I'm building, and the 5/16-18 threads seated cleanly every time — no binding or galling even on the third or fourth re-tighten. At 4 inches long, they've got plenty of reach for thicker stack-ups, and the thermal black oxide looks like it'll shrug off shop grime.