Features

This product features two sides —
one for shaping, “Fine”, and the other for finishing, “Ex-Fine” — which are distinguished by a mountain-shaped mark.
Being slim (1.0mm) and lightweight (13g), it allows for gentle filing of the nails and can be used with both pushing and pulling motions.
Furthermore, both ends are rounded for safety reasons.

For Shaping (Fine)

This surface, approximately equivalent to
#800 grit sandpaper, is designed for nail shaping.

For Polishing (Ex-Fine)

This surface, approximately equivalent to #1200 grit sandpaper, is designed for nail polishing and finishing.

For convenience 

Comes with a dedicated carrying case to protect the finishing surfaces.

For cleanliness

Stainless steel makes the file washable for easy and hygienic maintenance.  
Once washed, thoroughly towel-dry the moisture to store it in the carrying case.