These nail files are horrible. They are too flexible and too weak. Thy bend too much when I am trying to file my nails. The grain/sand paper part is very fine and not gritty enough. I have average strength natural nails and this left them uneven and they kept snagging on fabrics.
I just bought a large pack of nail files at the Dollar Tree for $1 and they are 100 times better then these. I just threw them in the garbage.