M5-0.8 X 55mm 소켓 캡 나사 | 버튼 헤드 육각 소켓 드라이브 | 전체 나사산 | 클래스 12.9 합금강 열처리 흑색 산화 (200 / 팩)

Used a dozen of these to secure a custom jig I'm building, and the 12.9 grade steel felt rock solid even under heavy torque. The black oxide finish also held up well against minor scuffs during assembly.

Finally, button head screws that actually seat flush without stripping the hex drive on the first torque. These M5s are perfectly machined and the black oxide finish feels nice and durable. I've used them on three jigs so far without a single issue.

Installing these in a precision assembly was straightforward—the hex socket seats firmly without any wobble. The black oxide coating looks uniform and seems durable, and the 55mm length was exactly what my fixture needed.