Philips Sonicare 3100 Series Electric Toothbrush - Sonic Toothbrush with Advanced Sonic Technology, Pressure Sensor, Two Intensity Settings, Smartimer & Quadpacer, White, Model HX3681/03

[This review was collected as part of a promotion.] This is the third Norelco Sonic toothbrush I have owend. After many years of good service, the other two batteries finally wore out. The 4100 series is, of course, an advanced version of the ones I used befrore and has been performing even better. I am very pleased with this purchase and expect better dental reports as it has been over 5 years since the previous one finally would not accept a battery charge - the batteries are not replaceable (sealed). While the Owner's Manual states that you can leave the brush on the charger, I had done that with the first two and I think that is why the batteries eventually built up a resistance to continued charging. This one is allowed to sit on the counter (flat bottom is stable and the brush air dries). On the first charge, I got 3 weeks of daily use before it indicated a need for a recharge.