This is a battery for iPhone 11 Pro Max. The spare battery replaces the original battery if it has become damaged, stopped charging or is not charging properly. This is a AAA battery. An iPhone battery is set to have 80% capacity left after 500 charges. As the amount of charges exceeds this the battery will need to be charged increasingly often. To avoid this, we recomend replacing the old battery with a new one. When the change of battery has been made the phone will sometimes display a warning message regarding “genuineness”. This occurs even if the replacement part is an original Ap product. This message can be ignored and will not effect the performance of the device.