This is a unique Crown die trial strike (1957) for preparing the copper-nickel Crown for Queen Elizabeth II in 1960. It is 38.5mm which is within tolerance for the 38.61mm Crown size struck in 1960.

It was either struck with two obverse or two reverse dies since it was a trial strike. PCGS authenticated and certified it MS 62.

Although there are many smaller trial strikes (1957) testing new metals, designs and compositions, this is a unique Crown size die trial in copper-nickel and has an identical obverse and reverse.

Die Trials are featured in chapter 13 of my
NLG award winning book, World's Greatest Mint Errors.