I love this little 7-inch plastic file and depend on it to keep my hard-working fingertips smooth. It has two sides with different grades of sanding surface - medium/fine (aka 100/180 grit).
Say goodbye to rough finger skin that snags on fabric or becomes cracked and painful. Trust me, you'll find this little file as "handy" as I do and you will go nuts if you accidentally misplace it!
P.S. This is a thoughtful and inexpensive gift for your hardworking friends.