The internal dimensions of the dovetail were not accurate. I had to put it down to fit my tool post. This also speaks of 1/2" tooling, but actually the clamped size was about .515". So the tool I had marked 1/2" was actually a .495" which would not tighten. I grounded the radius of the clamp slider which made it low enough to work with. Everything is fine now, but it took some effort to get there, hence 3 stars.