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 am 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 years none have since these units are not repairable expect them to last a year maybe twothis 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 batteriesdo not buy the suggested newer model of this for it is not the same as the others it a motor driven thing with a huge head that is hard to use and does not do near as good of a job it is small and cheap junk