I didn't have high hopes for this hole saw and only planned to use it for drywall. If so, I would be very happy. Unfortunately, you can see that in the pictures. I used this on 1/2" drywall and as you can see in the picture it couldn't even do that trade. They seem to use two pins to hold everything together. This would be fine unless they have a very weak pivot would use.. Both pins broke cutting just one hole.To compound this problem there is a "C" clip on the back which is too small for own use.In the second picture you can see that the screw went into the "C" clamp after the pins broke. Good luck unscrewing it without a vise and a lot of unnecessary work.