It's an external battery pack much like the Mophie Powerstation Plus, but it has a suction cup system that allows it to stick to the back of the iPhone, which means the iPhone can still be used as normal for the most part while charging is taking place.
We went hands-on with the PowerSkin Pop'n 3 battery pack and we thought the suction cup system was a handy feature. The suction cups themselves were a bit weak, but an added sticky pad in the middle of the battery pack assures that it sticks firmly to the iPhone.
We also liked the built-in Lightning cable that's just the right length for charging, and the LED indicator that let us know how much charge was left. The Pop'n 3 works best with an iPhone with no case, but it'll also stick to flat, smooth cases.
The Pop'n 3 battery pack has a 4,000 mAh battery inside, which is enough to charge the iPhone 6's 1,810 mAh battery to full twice over, and enough to give the iPhone 6 Plus with its 2,915 mAh battery 1.5 charges. It's only suitable for the iPhone, though -- it won't be enough to fully charge the 7,340 mAh battery of the iPad Air 2.
Like most battery packs, the Pop'n 3 charges via micro-USB. Compared to the iPhone 6 and 6 Plus, the Pop'n 3 is not quite as wide, allowing it to fit comfortably on the back of the phones. It's 2.36 inches wide, 4.41 inches tall, .49 inches thick, and it weighs 3.81 ounces. That's just over half the weight of the iPhone 6 Plus, so it's quite pocketable.
Compared to several other battery packs on the market, the Pop'n 3 is a bit less impressive when it comes to capacity, but its unique portability and its price point make up for the lack of juice.
The PowerSkin Pop'n 3 comes in three colors to match each of the iPhones and can be purchased from the PowerSkin website for $49.99.