2-4-1/2 X 4" 內六角螺絲 | 六角驅動 | 全螺紋 | 合金鋼 熱處理黑色氧化

Used a full box of these for a jig build and the black oxide finish held up perfectly against the coolant splash. Threads cut clean into hardened steel without a single bind, and the hex socket drive felt rock-solid at high torque. Just what I needed for precision assembly work.

The hex socket drive grabbed my Allen key cleanly with zero stripping, even under heavy torque on my fixture jig. Fully threaded all the way up, so the grip on my precision assembly is solid. These are exactly what machine work calls for.

The black oxide finish on these screws looks sharp and holds up well during assembly—no flaking or rough edges. Threads cut cleanly into steel, and the hex socket drives true without stripping. Exactly what I needed for a jig rebuild.