Diamond drill bit. Suitable for natural nails as well as artificial nails, great tool for any professional manicurist or beginner. Used in hardware manicure and pedicure: - Cleaning up nail cuticles - Smoothing and shaping gel or acrylic nails - Helps manicure to last longer Diameter of the working part: 3,1 mm Shank diameter: 2,35 mm - fits for most electric manicure machine on the market Grain size: small (Red)