REMOVE THE HARD SKIN MORE QUICKLY ---It has 2 differentes rollers and 2 type of speed. You can use the white roller to remove the hard thin calluses, and with the black roller to remove the thin calluses.LONGER BATTERY LIFE ---Unlike other roll pedicure devices that contain batteries (<600 mah), ours are 2000 mah (longer lasting), so it has a longer usage time and a longer life.2 TYPES OF USE ---Blue light is always in high speed mode, up to 2400 rpm, blue light flashes in low speed mode, up to 1800 rpm. You can select different heads and speeds to remove different thicknesses of calluses.SCIENTIFIC HANDLE DESIGN ---Designed with a more powerful engine and improved ergonomic design, it is portable, works fast, safer and more efficient than using it.Super QUALITY ---We pay close attention to the quality of the product. .