Compatible with Philips Sonicare Elite Toothbrush Repair NiMH 2150mAh 1.2V. Please, notice that to replace the battery it is necessary to disassemble the Toothbrush. All Toothbrushes require soldering to install battery. If You are not sure that can disassemble the Toothbrush and install the battery correctly, we recommend to ask a specialist for help. The battery size is 1.65 x 0.67Inch (42x17mm), before making the purchase, please make sure the size of your old battery is the same. How to determine polarity correctly: The positive contact + is where the notch on the battery is, where there's no notch, it is minus -