As useful as all the reviews indicate
I bought this product because my heels become very rough in the winter.  The dry skin was catching on my socks and sheets and annoying me.  I had tried a manual file, but that was totally ineffective.  This product is easy to charge and use.  It holds it's charge for at least 40 minutes.  I used the foot file on dry feet every day for 4 days and now am using it once a week as a maintenance routine.  It is gently run back and forth over the skin to grind away the dead skin.  There is no discomfort.  There is quite a bit of foot dandruff created. Follow with some moisturizer and put your socks on! Voila!
Rating: 5 stars