I used these all the time before I found out how much better crystal files work. As far as this type of nail file goes, they're not horrible. My main problem is how rough they are, and how quickly they're rendered useless due to the sandpaper finish getting rubbed off. Still, I recommend switching to a good quality, reusable crystal file.
As Old-Skool as you can get and can do more hard than good.
In a pinch I might grab one of these from outta my grandma's powder-room cabinet but on my own accord? Nah. Too rough - like sand paper. I prefer a ceramic (Amera) or glass file for a smooth free edge.
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.