1/4-20 X 5/16" 滾花杯點內六角止付螺絲 | 合金鋼鍍鋅 (250 個/包)

The hex socket drive makes them easy to crank down in tight spots, and the knurled cup point really bites into the shaft. Solid grip for the price, though I wish they came in a smaller bulk count.

Finally found a set screw that actually bites into the shaft instead of slipping—the knurled cup point really holds tight under vibration. Perfect for locking down a pulley on my small engine build.

The hex socket drive made tightening these down in a cramped bracket a total breeze, and the knurled cup point bit into the shaft without slipping. For 250 pieces at this price, the zinc plating looks clean and even across every single one I’ve used so far.