Battery for 3GS iPhone, 1600mAh. Installation of this battery requires almost complete disassembly of the iPhone. Because of the extra time involved, we charge a slightly higher installation fee. Installation Options Self Installation - You purchase and install the part. Gadget Repair Installation - Purchase the part you need or the part we identify during our Diagnostic Testing, ship your gadget to us if we don't already have it, and we will professionally install the replacement part and test for the proper operation of your gadget.