I changed my battery of my iPhone 4S with it and my phone works fine. I am satisfied. Warning against dismantling by phone: many say it is easy but I spent a good ten minutes trying to take off the original battery. Apple uses a demented glue that firmly secures the battery so that you can risk damaging the components by wanting to. Provide good tools and act with dexterity firmly but tactfully. Above all, do not hurry.
EDIT: after 3 months of use the charge is gone. I do not recommend!