HI Vintage Rose -
Your measuring cup looks like the one pictured on page 117, Florence's Kitchen Glassware of the Depression Era copyright 1995/updated 1997
It is on the 5th row, 2nd from the right - but it is an advertising one with the words "STICKNEY & POOR" Boston Spice Co.
The Fire King ones shown appear to have a slightly different top edge (no band) and the foot of the FK ones are slightly rimmed. Yours looks perfectly flat as does the one in the book.
Unfortunately Florence does not name the maker of the advertising measuring cup.