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 blunt or the drill was running backwards. I threw away the last 4. Now I have a set of 6 bits that suit my purposes. I'll see if I need to buy a replacement kit from say Bosch or I can get by with two good ones for now. I will never buy this brand again.