M6-1 x 40mm 內六角螺絲 | 低頭內六角驅動 | 部分螺紋 | 10.9級合金鋼熱處理黑色氧化物 (200個/包)

The low head profile cleared the tight clearance I have on my jig table, and the hex socket drove in smoothly without stripping. The black oxide finish feels dry and grippy, not slick like some coated screws I've tried. For 200 pieces at this alloy class, they're a solid value.

I was worried the black oxide finish might be purely cosmetic, but it's held up perfectly against oil and chips during my tooling setup. The hex socket drive really helps torque these into tight spots without stripping.

I needed a batch of fasteners for a jig build, and the partially threaded design on these made alignment much easier than fully threaded screws. The black oxide finish feels durable and hasn't chipped during installation.