I measured these bits with a precision caliper, but I didn't need a precision caliper to show that these bits were everywhere with a difference in size. One or two of each size I've tested are accurate to the tenth of a millimeter. Especially with these sizes, these errors account for over 30% of the difference between what size they should be. The grinding at the tips of these bits is also uneven. It's like someone doing it for them by hand. I've had worse, but I've also paid a lot less for it.