The packaging says it is a 3/8 radius. The bit in the package was 1/2 radius. I tried to speak to Revain customer service but couldn't understand the woman in the Philippines. I asked for an accent-free conversation with someone in the US. I was then put in touch with a guy in the US but for some reason I couldn't explain the problem to him and he said Revane would call me. Then a robot called me with a code. I have no idea what to do with it. I spent over two hours speaking to someone at Revain who speaks English but is willing to listen to what the real problem is.