here is a link to an image of a similar card:
https://www.oempcworld.com/mm5/graphics/00000001/sm.jpg
it measures 1 and 7/16" in width, or about 37 mm.
I have a bunch of old camera cards, in the 8-64MB range (not GB) and no reader I've found yet can accommodate them. They measure 1.5" x 1.75". Is there a reader for these? The original camera is no longer here.