1-1/4-7 x 3-1/2" 소켓 캡 나사 | 접시머리 육각 소켓 드라이브 | 전체 나사산 | 합금강 열처리 블랙 옥사이드

Used a dozen of these to rework a jig I've had for years—the black oxide finish left zero residue on my fingers, which was a nice surprise for a thermal-treated screw. Threads cut cleanly into the alloy steel frame without any binding, and the flat head sits flush enough that my calipers didn't snag

The black oxide finish on these screws is holding up perfectly on my milling machine jig, no rust after three weeks. Tightened them down with a hex key and the fit was snug, exactly what I needed for the tooling setup.

Installing these on a jig I'm building and the hex socket drive gives a really solid grip, no stripping at all. The black oxide finish seems durable and the threads are clean all the way down. Exactly what I needed for heavy-duty tooling work.