High quality Korean emery board. Light weight. Re-useable (washable). 50pc/pack. Nail file grit guide: 80/80 - very sharp and rough, used for removing outer gel or acrylic overlays. Not recommended on natural nails. 100/100 - medium sharp and rough, used for preparing nail plate before applying gel or acrylic and for shaping artificial nails. 180/180 - less sharp and rough, for finishing off filing artificial nails. Recommended on natural nails. 240/240 - soft filing. Recommended on natural nails.