Thank you to Thomas, a reader from New Jersey, who sent me 2 pictures with this to say:

Some of the bigger files in my collection.  Top two have handles I turned.  The others are mostly Skrooz-On brand, in the biggest sizes.   The German file has such a huge tang, it is in a dowel-filled piece of tubing with a motorcycle grip shoved on.  

I have 2 spares for the 20" which I consider a human-powered milling machine, and mostly use on aluminum.  All of these were gleaned from old hardware and mill supplies in NJ - all of which are now gone.  Most of these were "last one(s) in the box" and nobody buys them anymore deals.

The smallest tanged file I have is a 2" Swiss pattern round file, which looks like a big sewing needle.  I got that in a random batch from a now defunct jeweler's supply.  I have a few 3", many 4" and an uncounted number of 6" through 12". 

Simonds plant, Newcomerstown, OH, 2011