This burr is the one that will reduce most hypertrophied nails and the average callus.  It is a little large to use safely on soft corns.  You can use this burr in most places.  It will be a little small when you need a large one and a little large when you need a small one.  No one instrument does it all.

 

This burr is designed to reduce the heavier callus, or nail tissue.  You should use a  light brush stroke and very light pressure on the tissue.  The nail may need to be smoothed after using this burr, while callus tissue will be smooth.