5/16-18 X 4-1/2" 圓頭內六角螺絲 | 內六角驅動 | 合金鋼 熱處理黑氧化物 (225 / 包)

Just finished a jig build and these button heads held up perfectly under the torque—the thermal black oxide gives them a nice, even finish that blends right in. I’ve used cheaper screws before that stripped, but these hex sockets engaged my driver cleanly every time.

These button heads sit perfectly flush in my jig fixtures, and the black oxide finish hasn't shown any wear after a week of heavy use. The hex socket drive makes them a breeze to tighten in tight spots.

Had to replace some worn fasteners in a jig setup, and the black oxide finish on these matches perfectly while offering good corrosion resistance. The hex socket drive makes installation straightforward with a standard Allen key, and the 4-1/2" length gives plenty of grip for thicker assemblies.