Review (4/5): Tape the seam to keep dry
This model has a habit of water getting into the battery area because of the O-ring not being ideally sized for the sealing area. To alleviate this and to keep water from entering, put some tape around the seam. Also, dry after using and store on it's side (note raised plastic ridge on the side for this purpose)
This model works just as well as my previous full sized sonicare with a charger base. Also it can be used overseas unlike some of the other models. And, when the other model's battery wears out you have to buy a whole new unit!