Digging around looking for something and this is laying in a box from 'who knows when....'
I don't think this is your regular run of the mill baling wire. . .
The trademark Nilstain indicates Amax Metals corp 'ferrous alloys for electrical purposes'. Wilbur Driver was a marketer of
lots of different wire products, probably they did the final shaping of the wire. It's possible that this is a thermocouple
alloy, Wilbur Driver made a bunch of those... and 99% pure iron is a standard thermocouple wire which might
have borne this or other tradenames.
Best other idea I can come up with, is this is a weldable wire that can be made into resistors/heating elements (which, today, are usually
nichrome, i.e. nickel-chromium, not ferrous). Third-best idea, is that it's a weldable wire that is used to build
vacuum tubes' internal structures.