This product is very poorly designed especially the supposed piece holder which is a joke & potentially dangerous. Someone posted that the base was cast iron, it's not, it's very light gauge steel. Actually I sent it back because I found it an accident in the making. When I complained to the company about the product, they were a bit resistant to accepting it back & I had to pay $10.00 shipping to return it. I just felt that using it on a tool that was spinning @ 11K RPM's wasn't a good idea. On the plus side, the arm seemed to be fairly stable but after opening the box & looking at it's construction, I just put it back & started the return process. Another thing is, they ship it without any washers that are most essential if you were to try to use it because I'm sure the vibration would cause the bolts to loosen & cause more problems or injury.