4mm Cobalt M35 Drill Bits (5 Pack), Metric Black and Gold Coated Twist Drill Bits for Hard Metal, Stainless Steel and Copper

These bits are very strong. I bought them for knife making, so I’m using them to drill through 1084 carbon steel, and they have no trouble going through the metal. Lube them up before drilling, and go slowly, and these should last a long time.

Works as advertised no Problems yet. Look and feels appropriate. Reasonable

Worked well

Dull after a few uses.

Good for price

I’ve been using the HLOFIZI 12.5mm cobalt drill bits for a range of projects, and they’ve quickly become my go-to choice. From the moment I set them into my drill press, the installation was seamless no fuss, no wobble, just a perfect fit. The form feels solid in hand, and the precision of the 135° split point makes starting holes effortless without any walking. Functionally, they cut through stainless steel and copper with clean, burr-free accuracy, and the optimized flute design clears chips fast, keeping the process smooth. Durability is where these bits shine: they hold their edge even after repeated passes through tough materials, resisting heat and wear far better than standard HSS bits. For the price, the value is outstanding getting professional-grade performance at a fraction of what I’d expect to pay at a hardware store. In short, these bits deliver precision, durability, and ease of use in a package that feels like a smart investment every time I reach for them.

9 holes both toasted. Used oil also

The 10MM drills were tested drilling 1/4" mild steel and 1/8" 304 stainless. The bit drilled both metals easily in a drill press with cutting oil. The holes were clean and measured 10MM. A drill press helps when drilling larger holes in metal. The two pack allows for a spare if one of the bits gets dull.