Which architectures should I include for native libraries with Unity building for iOS?

I have a large native c++ library that I include into my Unity project. I'm building a fat binary containing various architectures, but I'm not really sure which I should be including.

Note my application requires iOS 7.1 or greater.

In my library I'm currently including:

arm7
arm7s
arm64

Note, this is currently for a Mono build (not IL2CPP).

Is this correct? Do I need both arm7 and arm7s? Should I be...

Which architectures should I include for native libraries with Unity building for iOS?