eForCity Battery Compatible with Apple? iPod? 4G 4th Gen Photo U2 20GB 40GB Keeps the music playing on your Apple? iPod? with this replacement battery. Comes with the necessary tool to open up your iPod?. This is a high capacity / rechargeable Li-Ion (Lithium Ion) battery with premium cell. Voltage: 3.7 V Dimension: 1.94 x 1.37 x 0.13" [49.28 x 34.80 x 3.30 mm]. Accessory ONLY. iPod? not included.