The Cuticle Bit Ball features a wide diameter ball-shape with a coarse grit that provides a safe and effective way to clean the eponychium and remove hard skin above the nail plate. It's perfect for removing loose cuticle lifted from the nail plate, and finishing and smoothing of the side and back walls while doing manicures and pedicures, including callus and sidewall polishing.
More info:

Diamond Bit
Coarse Grit
Standard shank size 3/32" (fits all professional nail e-files)