I bought this product for 2 weeks for my iPhone 3GS. The spare battery is worth the money, is 100% individually cut for the iPhone and the handling very easy (installation and removal). The total duration of the batteries has more than doubled. A small drawback, however, one must take into account (the total weight becomes larger). Despite built Powercase the iPhone is still very good in the hand. Can recommend the purchase of this product without restrictions.