Fibreglass is highly resistant to wear, making it ideal for nail filing. The file consists of two sides, each with fibreglass grains of different degrees of intensity, to obtain a micro-polishing that strengthens the nail and makes it more resistant.
The coarse-grained side is used for filing and shortening the nail, while the fine-grained side is suitable for polishing roughness and outlining the contour. Regular use helps prevent nails from chipping.