I bought this hole saw to cut holes for hard ducts. It worked great. Clean holes that are easy to cut. Take your time and let the saw do its job. If you try to apply too much pressure hoping the saw will cut faster, you'll just get stuck. This next part has nothing to do with a hole saw, just for reference in case you're installing an air duct like me. The saw will cut a 6" hole, but a 6" rigid channel is measured by the inside diameter. Therefore, the thickness of the duct does not allow it to pass through the hole cut by this saw. It was a mistake on my part, not a defect in the saw. The hole saw did exactly what it was supposed to and did it very well.