HOLO-KROME 60110 3/8-16 x 2-1/4" 內六角螺絲 | 平頭內六角驅動 | 合金鋼熱處理黑氧化 (50個/包)

I needed a true flush fit for a jig rebuild, and these flat head screws are exactly that—the 3/8-16 threads engaged smoothly, and the black oxide coating seems durable enough for shop use.

The flat head sits perfectly flush in my jig, and the black oxide finish gives them a nice friction grip when tightening. Used a full pack on a tooling frame and not a single one stripped.

Finally, a flat head hex screw that actually sits flush without needing extra countersinking — the 3/8-16 thread grabbed perfectly in my jig. These hold solid under torque, and the black oxide finish has held up well after a few adjustments.