M4-0.7 x 18mm 소켓 캡 스크류 | 육각 소켓 드라이브 | 전체 나사산 | 12.9급 합금강 열처리 블랙 옥사이드 (900개/팩)

The black oxide finish on these screws is holding up perfectly in my precision assembly setup, no rust or wear after repeated adjustments. Torqued them down with a hex key and the socket drive engaged cleanly without stripping—exactly what I needed for tight spots.

Used these to replace hardware on a jig fixture and the black oxide finish cleaned up nicely without any residue. The 12.9 grade steel feels noticeably sturdier than standard screws I've worked with.

Got a full box of these for a jig I’m building, and the hex socket drive made driving them into tight spots painless—no stripped heads at all. The black oxide finish feels properly grippy too. Solid value for a 900-pack that’s clearly meant to hold up in real use.