Review on Professional Nail Files for Natural and Acrylic Nails - 12pcs Fine Grit Emery Board Nail File Set - Manicure Tools for Coarse and Fine Fingernail Files (100/180 Grit) by Lynn Warwick

I use this file on my natural nails and I have found it to offer a good combination of softness and hardness. This crumb is definitely something for natural nails. I used one about 3 times a week for a month. I wash it after every use. I carefully file the entire nail only when necessary. I take vitamins to strengthen the nails. I don't know how it will be on brittle nails. The hair, nails and skin supplement has definitely strengthened my nails, taking them from weak to strong. Proper nutrition is also important. After a month of use I think it's lost most of its sand so I'll probably be changing it soon.