I bought this to use as a shaft coupling. I can't use it as intended because the hole doesn't fit the advertised size due to the changing radius. I can see where the radius starts to change, which means they're probably pressed to shape rather than forged or cut, which means almost all probably have the same error to some extent. So far I have bought this size and 1 1/2 inch version. Both have the same type of defect. I just ordered version 1 5/8 hoping they have fixed this issue or not affect all sizes of the collar. Use is not size critical, it appears to be well milled, no rough edges, screw slots are well cut and aligned, threads appear to be properly tapped and the screws provided fit.