A good alternative to trying to change the iPhone internal battery.
Works well and keeps the 'phone going for 3 or 4 days instead of less than 1 day as it was. You do have to make sure the 'phone is very firmly pushed into the case otherwise the connector doesn't mate properly. The case itself is quite sturdy and should protect the 'phone OK. All in all well worth the money and costs a lot less than the Apple one.
I found that changing the internal battery in an iPhone 6S was impossible! This is a much easier solution.