Mesuit is the size and shape of a battery case and, in fact, it actually functions as one, giving an iPhone 6 or 6s additional 1,700 mAh of power, or 2,500 mAh for the iPhone 6 Plus and 6s Plus.
The secret, however, likes inside the case, which hides practically the barebones of a smartphone, complete with a MediaTek MT6753 processor, 2 GB of RAM, and 16 GB of storage.
Data is exchanged between the two via Lightning connection. The Mesuit case supports a nano SIM for the Android part and both it and the iPhone SIM can be active simultaneously.
The Mesuit case for the iPhone 6/6s costs 999 RMB, around $150, while the larger iPhone 6 Plus/6s Plus version goes for 1,099 RMB, roughly $165.
This does look like a good battery case which let you run Android on iPhone. The battery case having 2500 mAh is also pretty nice to have. The specs of the case is good, but 16GB of storage is kind of low. I think the case should have at least 64GB of storage.