I've already used it to sharpen a long serrated knife, and a set of dull Forstner bits (mounted the round file in a drill press and ran it slow (~500 rpm) to touch up the bits' inside edges). Only tjing that works well for those sorts of jobs.
The file has a multi-purpose form; sharpener for edges and metal management device for smoothing material without the use of oil, water works great as a lubricant.
These Rods are great to stick in a backpack or leave lying at the desk. Sharpens very nice and easy. I got the 1000grit and it really hones it nicely - then hit it with a strop and it's razor sharp!