ATC 4Pack Cordless Phone Battery For Panasonic P-P511 PP511 HHR-P402 3.6V 2400mAh Ni-MH Brand New | Ni-MH | 3.6 Volts | 2400 mAh | Black 100% OEM Compatible - compatible with or Exceeds OEM Panasonic P-P511 Battery specs Masione replacement battery has an integrated microchip that prevents overcharging and lengthens battery life. Great bargain with excellent quality guaranteed. 1 Year Warranty