ATC 5Pack Panasonic P-P511 NiMH 2400mAh Phone Battery - for Panasonic P-P511, Energizer ER-P511, ER-P507 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