Material: [Scrub] Colour: [Black-Blue] Size: [6.2 cm] Easy to use and installation: the callus remover replacement roller replacement heads are easy to install and use and perfectly compatible with foot files. Material: Emery. Emery particles with a roughness of 24 to 59 microns are included with callus remover replacement rollers to easily remove dead skin cells. Application: For optimal results, we recommend soaking the feet in warm water before using callus remover replacement rollers to soften the skin. Tips: 1. After each use, remove the roll and rinse thoroughly. 2. For optimal results, we recommend replacing the roll after 10 to 12 times use of velvet replacement rolls. Double design: replacement rollers have a specially developed concave roller that fits tightly to the heel and removes calluses easily and quickly.