1.Gentle on sensitive skin 2.Ergonomic design 3.Two speeds 4,Uses 4 AA batteries (not incl.). Pedi Spin Callus Remover Pedi Spin includes two different types of treatment plates: Polishing plate and Finisihing plate. use the polishing plate for thicker, tougher callused skin and Finishing plate for smoothing out rough edges after the polishing plate treatment, then use it to maintain soft, smooth skin in between polishing plate treatments.