This bit is not advertised correctly. This is NOT a 3/8" end mill for rounding corners, it is a 3/32" end mill for rounding corners. The DIAMETER of the twist on it is 1/4" and the radius on it is 3/32". Don't be fooled into thinking this is a good deal. This is a terrible deal. You're better off buying from McMaster Carr, which is saying something.