because similar devices were poorly rated here on Amazon and have caused damage to some battery. I took the risk with my old 3GS and can say that this battery delivers what it promises. I have the first battery fully charged (until all 3 lights are lit steadily) then once completely emptied and then fully charged again. From this time he was already able to get most of his power;) I also find convenient that "charging cable" is directly on the device and does not need to be additionally taken. 1 star deduction, since it unfortunately somewhat shaky sitting on my 3GS and I'm afraid if I even unhappy the battery pack down / press the top of the dock connector breaks. Be careful here in any case, at least the 3GS
