High quality Korean emery board.
Light weight.
Re-useable (washable).

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.