On every iPhone battery, you'll find a so called APN (Article Product Number). It differs from model to model, and sometimes even differs between batteries of the same model. It is often concluded that specific APNs are only compatible with particular iPhone models.
In our experience, since the iPhone 4 there have been no problems with incompatible batteries. As long the voltage, capacity, and fit are right, the smartphone and the new battery can get by without any problems. Of course you should also pay attention to the quality. We check our batteries with elaborate procedures according to the DIN regulations.
This is why you can be sure that our batteries will rejuvenate your iPhone's performance.