The back of the battery case boasts its most important feature: an iPhone 4 backpack!

Jk...Probably.

While the Smart Battery needs its own external Lightning connector to charge and pass data through to the iPhone within, 3.5 mm headphone jack connectivity is provided in the form of...a hole.

As expected, the pass-through hole is perfectly sized for your iPhone's included Apple Earpods.

However, for anything bigger, you'll need some sort of adapter. No fancy studio-size jacks for this pack.