Best toothbrush made. [SEP] A great alternative to the expensive plug in version.  It has just as much power - maybe more.  Reliability is about the same.  You end up spending more for batteries, but the unit is much cheaper to begin with.  I'm not sure how much electricity costs are for the plug in model.  I subtract a star from both this one and the plug in model because of reliability.  Over the years I have had almost everything go wrong from dead batteries to bad switches to corroded wires to just plain dead.  The first one I had lasted 4 years.  None have since.  These units are not repairable.  Expect them to last a year, maybe two.<br /><br />This unit has the exact same mechanism as the expensive plug in model and uses the same replacement heads and is about the same size.  The batteries come out the bottom and there is an O ring seal there.  If moisture is allowed to enter it will mess up the battery compartment.  If you stand it vertically after use rather than laying it down it will last much much longer because the water drains off it.  I get a month, sometimes two, out of a set of batteries.<br /><br />Do not buy the suggested newer model of this for $15.  It's not the same as the others.  It a motor driven thing with a huge head that is hard to use and doesn't do near as good of a job.  It's small and cheap.  Junk.