“I first purchased a carbide 4" hole saw to drill through the red brick on my house. The carbide barely scratched the surface. This diamond core bit worked perfectly and only took about 15 minutes with resting everyfew minutes. I did not have any quality issues with the tool, and plan to use it again in the near future for a dryer vent. Others mentioned breaking the teeth, im assuming they used it on a hammer drill or something. Mine looks like i just removed it from the box. Very please with the purchase.”
