Review (3/5): These are very rough on natural nails.
I really liked the size of these and that they had different grits on both sides. The problem if using on natural nails is that one side chews away your nail and not even at all. It's like taking a saw blade to your nails.
The other side isn't quite as rough, but the "grit" just crumbles away as you file. I was very disappointed in these.