They are very poorly made. Bought a set of ten. As soon as I took them out of the packaging, I could tell that they weren't ground well. The drill seems reasonably well made, but the grinding of the tip of the rod is terrible. Some were wrong. At least one of them was sharpened at a negative angle, so it would probably drill a hole better if the drill was set to reverse. Out of a set of ten, 2 cut very well, 4 were marginal, and 4 required significant pressure to even cut, as if they were very…