M20-2.5 x 40mm 內六角螺絲 | 六角驅動 | 全螺紋 | 12.9級合金鋼 熱處理黑色氧化 (25個/包)

The black oxide finish on these screws is genuinely slick, and the hex socket drive seated perfectly with my Allen key the first time. For a 12.9 alloy steel cap screw at this length, they feel dense and solid—no wobble when torquing down my fixture plates. Exactly what I wanted for precision work.

The black oxide finish on these screws looks professional and seems durable—I used them for a jig build and they threaded cleanly without any binding. For the price of a 25-pack, the Class 12.9 strength is a solid deal.

I was able to tighten them into a steel jig without stripping the hex socket at all. The 12.9 alloy steel feels incredibly solid, though a bit pricier than I'd hoped for this size.