Eforcity Replacement Li-Ion Extended Battery for LG VX4400 / VX4400B Stay in touch longer by getting extended battery power. Latest Lithium Ion battery technology gives the best performance possible compared to other battery technologies such as Nickel Metal Hydride (Ni-MH). Integrated microchip prevents overcharging and lengthens battery life. Compatible with LG VX4400 / VX4400B Voltage: 3.6V