M12-1.75 x 80mm ソケットキャップスクリュー | 六角穴付き | 部分ねじ | クラス12.9合金鋼 熱処理黒色酸化 (50 / パック)

Needed a full set of these for a custom jig and the threads engaged cleanly from the first pass, no galling. The 12.9 hardness gives me real confidence they'll hold up under repetitive torque without stretching or stripping. Might grab another pack for spares.

The black oxide finish on these is impressively uniform, which made them look sharp in my jig setup. Threads engaged cleanly right out of the bag, and the partially threaded design gave me solid clamping force without bottoming out.

Used these on a heavy-duty fixture build and the black oxide finish held up without a single scratch during assembly. The partial threading made alignment noticeably easier than with fully threaded bolts, and the hex socket drive seated perfectly every time.