The most indispensable accessory for your Sony Ericsson cellular device is the battery. Unless you are need of a paper weight, even the most advanced phone is useless without power. Use this original Sony Ericsson BST-39 Battery as a replacement or spare to extend the talk time of your Sony Ericsson cellular device. Keep your Sony Ericsson cellular device working at optimum performance levels at all times. Just pop it in your pocket or bag and you’re good to go that extra mile, chatting with your friends, at work, or on the road.