Attaches the battery pack unit for the 20i to the back of an iPhone 6 Plus when in the leather case. Update Dec 9 2015. I have just uploaded a variation of the model which has smaller arms that clip to the iPhone. Previously the clip was wrapping right around and getting in the way of the screen. Hopefully this new model makes it better whilst still being secure enough.I've also attached the source 123 Design file if someone wants it to make further edits.