WRACO 45 Expo Blank

Would like to find out more about this blank, like the year it was made and its purpose. Thanks In Advance

see Chris Punnett’s .450 book pg. 88, and Dan Shuey’s WRACo Headstamps book(s) Vol. 2, pg 116 for information.
From Punnett: for the 1904, Louisiana Purchase Centennial Exposition but possibly also at other times.
& It’s a noise blank.

Many Thanks Pete, Have to get those books. Take Care