Product Description  Replacement Battery for iPhone 4S - Battery. Why should I replace my battery? Batteries in iPhones work like any other battery - they wear out with time. After about 6 months usage a decrease in battery life by 10-20% is usual.  Another 6 months later it's obvious that the battery needs to be charged more frequently than before.  Furthermore, when the battery is really worn out, it's common that the percentage jumps or switches quickly. In some cases the phone switches off when the battery is running low (at 10-30%) or when a high performance application, such as GPS, is being used.  To correct all these problems, a battery replacement can do the trick!  Good to know:  - No information on the iPhone will be lost if done as instructed - Designed to work with all iPhone 4 S variations  -Helpful tips attached to get the maximum out of your new battery - The battery is high above capacity 1715mAh li-ion designed for iPhone 4 S Disclaimer