The Grade 439 Extra Thin Extra is marked Extra on the movement it is a 21J movement just like the 438 and there is an obvious parallel between the 538 Illini and the 539 Illini Extra with the 438 Extra Thin and the 439 Extra Thin Extra. There is one example in the collection and with serial number 3904929 and total production of 330, similar to the 539. This example is in a nice gold case with a fancy dial and would have been one of Illinois more expensive products when sold. It may have been more expensive than any of the railroad watches. With no cap in the case it would not have been Illinois most expensive watch.
My count for the grade 439 is 370 produced. The entire series of grades 439-438-437-435 are a little enigmatic in that the majority of these did not carry the Illinois name on the dial and I have, so far, been unable to find any advertising or catalog listings for this model. Many came in fine solid gold cases with inlaid enamel detailing. View attachment 341064 View attachment 341066 View attachment 341065
This photo shows the four different grades that Illinois produced in their 12-size Extra-thin 1st model. View attachment 341219 More examples are shown in this thread. https://mb.nawcc.org/showthread.php?103396-Illinois-grade-437-12S-first-thin-model
Grade 439 also came cased in platinum, although I have what might be the only example. I have never seen another Illinois pocket watch cased in platinum. The case is unsigned. The dial might have been refinished.
