The iPhone 7 battery will fit and work just fine in iPhone 6s. You only need to bend iPhone 7battery ribbon in s-shape (as I did) because it is longer then iPhone 6s ribbon. Make sure to use an original battery otherwise The benefit will be very subjective rendering the whole operation useless. Another thing I noticed after a prolonged use and several drops: The phone stopped charging . The breakdown revealed that the battery ribbon partially disconnected from the socket. It’ it's either the battery was fake or the iPhone 7 battery connector was thinner. I put some tape on the backside of the metal plate holding the battery connector to the phone body. no problems since then.--[br]