Review (4/5): Nice, strong nail files with rough edges.
Most nail files have smooth edges. Sometimes you need to get at a narrow place and then your standard nail files with their smooth edges don't help. These files have filing surfaces on their edges which I like a LOT. See the picture.
The one thing I don't like about these files is that the wide side actually quite narrow making it harder to "aim" them properly. Other than that these are great nail files and I am glad I got them.