HOLO-KROME 60130 1/2-13 x 1-1/2" 內六角螺絲 | 平頭內六角驅動 | 合金鋼熱處理黑色氧化 (50/包)

The flat head sits flush perfectly in my jig setup, and the black oxide finish held up well against my wrench without marking. These snugged down evenly with no thread binding.

Installing these in a precision assembly was a breeze; the hex socket drive seated perfectly without any cam-out. The black oxide finish on the alloy steel feels tough and should resist rust well in my shop.

I use a lot of these in jig building and the black oxide finish on them is really consistent, no burrs or rough edges out of the box. Threading went smoothly without any binding, and they cinch down tight without stripping.