I want to find a good leather belt case for my iPhone 4S that will allow me to have enough room to fit the phone and an external battery case like Mophie Air into it. When looking at the ones available, I know it will work with just the iPhone 4 but it does not say how much spare room they have or if they expand any in the compartment. Can anyone tell me if they use a battery case with a belt case too and if so what to get? I would like to keep my iPhone in my jacket or pant pocket most the time, but there are times when I need the freedom of a belt case but don't want to remove the external battery case it is in. Thanks for any suggestions.