NEW MUGEN 4500mAh XL EXTENDED BATTERY + DOOR COVER FOR HTC THUNDERBOLT ADR6400 Unleash the potential of your phone with the most powerful battery on the market for HTC ThunderBolt 4G This 4500mAh battery will last for about 3x longer between charging cycles than the original 1400mAh HTC battery Comes with a new custom door cover No Memory Effect More Power = More Fun!