HOLO-KROME 87090 M6-1 X 15mm 육각 소켓 캡 나사 | 접시머리 육각 소켓 드라이브 | 합금강 열처리 블랙 옥사이드 (100 / 패키지)

I needed some strong screws for a precision assembly, and the black oxide finish on these gives them a nice, uniform look. They thread in smoothly with no binding, and the flat head sits perfectly flush.

I bought these for rebuilding a jig fixture at work, and the black oxide finish held up perfectly against the cutting oil without any signs of rust. They drive in smoothly with a hex key and grip tight without stripping, which is exactly what I needed for precision assemblies.

The flat head sits perfectly flush when countersunk, which made a huge difference in my jig assembly. The black oxide finish also gives them a nice uniform look without any residue issues.