The larger side is called the rough side; The opposite is fine. When using, one - way grinding armor, not back and forth.

Such as:

Sand bars: coarse particles, mainly used for al crystal, phototherapy a basic polishing; Hair in crystal, phototherapy, nail plate before, natural nail grinding.

Sand bar 180# : fine granule, mainly used for repairing the last a around the finger skin of quartz crystal and phototherapy armour. Polishing of crystal and photometric nail surface; Shave your nails.

Sponge file: coarse granule, mainly used for polishing quartz crystal, phototherapy and nail polish. Etch natural nail polish.

Sponge file 180# : granule fine, mainly used for natural nail polish.