Does the language "Pat. App'd For" on the case indicate that you've got a first run of that model?
I just picked up a '38 Rite-Angle with that language on the back. It looks just like the one in the 1938 ad (i.e., not engraved like the later versions). Below is an excerpt from the '38 ad. I believe it's the earliest picture we have of the Rite-Angle.
