For Iphone 3gs Battery 100% New 1420mah Replacement Battery For Iphone 3gs With Repair Tools Kit - Mobile Phone Batteries - AliExpress
I was planning to use my old iPhone 3GS for weekend project but I discovered that the screen was popped out and the back was bulging, I took it apart and this
Conrad's iPhone and iPad blog: iPhone 3GS battery replacement: not for the timid