HOLO-KROME 61058 1/2-20 X 1-3/4" 內六角螺絲 | 平頭內六角驅動 | 合金鋼 熱處理黑色氧化 (50顆/包)

Used these on a tooling jig rebuild and the black oxide coating held up well against minor abrasion. The flat head sat flush in the countersink without needing to chase the threads.

The socket drive seated perfectly on my wrench with zero wobble, and the black oxide coating has held up through a week of clamping jig adjustments without a speck of rust. These are the first flat heads I've bought in bulk that didn't need chasing with a tap before use.

The thermal black oxide finish on these screws gives them a nice, uniform look, and the hex drive seated perfectly in my socket driver without any stripping. They worked great for securing a heavy fixture to a machine table.