You do not need a special back cover to use this battery This package is specifically designed for the cellphones we list here, if your cellphone is not in the list , then it's not for you. These batteries does not come with NFC (Near Field Communication) feature. 100% Brand New. 1)AC/USB Desktop Battery Charger : * Quick charge with automatic constant current control prevents battery from over charging, short circuit, and electronic shock. * Charge your cell phone battery without the phone. * Also work with OEM (original) battery. * LED charging light indicator. Turn red in charging, turn blue when done. * Input: AC 100-240V 50/60Hz 150mAh. * Output: DC 4.2V 350mAh ± 50mA. * USB Port Output: 5.2V 800mAh. * Use this charger to charge the stock battery as well, swap one out when the other dies. 2)New 4000mAh Rechargeable Li_ion Battery: * High quality Li-Ion battery. * Battery Type: Lithium Ion. * Battery Capacity: 4000 mAh. * Voltage: 3.8V. * The best spare battery for your phone. * Best Replacement for the original battery with comparable standby and talk time . * Our battery is sent out with little or no power, so please charge it for about 6 - 12 hours before using. * Keep an extra battery on hand for extend standby and talk times. * Integrated microchip prevents overcharging and lengthens battery life. * This Battery could also be charged in the phone directly thru the cell phone charger.