I sharpen my chainsaw blades with a Dremel moto tool, have found the Dremel brand bits to be the best but very expensive, tried many other bits but always disapointed, these seem to be all uniformly sized and after the first one broke after a few sharpenings, the second one is going strong. The price difference makes these a bargain, will be ordering a second set, should be enough to last me for many years. I sharpen saws about twice a week.