I have seen a lot of files, but this one is new to me.


FEB 220 by skipskip, on Flickr


it's smooth on top, fine file teeth on the bottom


what's it called?

Skip

That is a Barrette file. We used then to smooth edges of shims hanging out from edges of punches. No teeth on back kept from damaging surrounding components.

It's called a barrette file.
Graeme

Don't feel bad, there are perhaps 30 or so file shapes that would be considered 'common', and several hundred more 'special' patterns ;P
And that doesn't count the fact that most of them came in several different grits....