HOLO-KROME 43016 1/4-28 x 3/16" 滾花杯端內六角止付螺絲 | 合金鋼 熱處理黑色氧化 (100個/包)

The knurled cup point bites into the shaft nicely and holds firm under torque, which is exactly what I needed for a stubborn clamp setup. The black oxide finish looks clean and the alloy steel feels solid right out of the package.

The hex drive fit my socket wrench perfectly, and the black oxide coating on these 1/4-28 set screws seems tough enough to resist rust during assembly. They snugged down firmly into the tapped holes without any wobble.

Perfect fit for my mini lathe’s cross-slide lock, and the black oxide finish helps them resist rust in my damp shop. I used one to hold a gear on a shaft, and the cup point bit into the metal securely without slipping. These are solid pieces for the price.