Sure, it's just an iPhone battery case, but what marks this one out from the many others is the manufacturer: Apple.
The US$99 iPhone 6s Smart Battery Case is the first sign that Apple is ready to acknowledge that its phones are too thin to contain adequate batteries. The case adds 80 percent to the battery life -- and about 100 percent to the thickness -- of an iPhone 6 or 6s.
Unlike most third-party battery add-ons, the back of the case isn't flat, but has a bulge in the middle housing the battery.
Apple claims the iPhone 6s allows you to surf the Internet on LTE for "up to" 10 hours, a figure that could reach up to 18 hours with the external battery. The battery could also boost talk time from up to 14 hours to around 25, while video could play for up to 20 hours rather than 11.
The catch is in the words "up to" -- and Apple is by no means unique in using them: Pretty much every electronic device manufacturer does the same.
If you spend your days in an office with subdued designer lighting in hyper-connected Silicon Valley, where the nearest cell tower is no more than a few hundred meters away, you're going to get something close to the maximum theoretical battery life as your screen dims and the phone whispers to the nearby network.
For the rest of us, lighting is harsher and cell towers more distant, so our phones crank up the brightness and shout to the network, draining their batteries all the faster. That "all-day" battery can often be empty long before it's time to go home.
It used to be possible to keep a spare phone battery for situations like that, but one of Apple's innovations with the first iPhone in 2007 was to make the battery non-removable, a feature it has replicated in every model since, and which other manufacturers have since adopted too.
One justification given for using non-removable batteries is that without the need for a removable protective cover and clips to hold it in place, the phone can be made thinner -- or the battery can be bigger for a given thickness of phone.
Until now, Apple has chosen the former course (as have other manufacturers), making phones ever thinner, frustrating many who would like to be able to use their phones for longer and who would barely notice if their phones were a millimetre thicker.
They'll certainly notice the additional thickness of the iPhone 6s Smart Battery Case, which appears to add about 7 mm to the 7.1 mm iPhone 6s, to judge by the photos Apple has released. Had Apple chosen to make the iPhone 6s that much thicker to begin with, it may well have been able to boost the phone's battery life by 400 percent, not 80 percent.
Maybe it just wants a slice of the profit that the many other manufacturers of external battery cases are making -- or maybe Apple is testing customer acceptance of a thicker, not thinner, new phone.