In a surprise move, Apple just announced an external battery case for the iPhone 6s. Named the iPhone 6s Smart Battery Case, the battery extends the battery life of your iPhone 6s by up to 25 hours. The new accessory is available in black and white for $99 starting today.

Let’s start with the design. Apple is using silicone as the main material like on its other cases. The company doesn’t disclose the capacity of the battery except that you’re supposed to get 18 to 25 hours of extra battery.

Like third-party battery cases, Apple uses a Lightning male port at the bottom to plug your iPhone. You can charge the case using a traditional Lightning cable — most third-party batteries rely on a microUSB cable, so that’s one less cable to carry around. Apple’s accessory also works with the iPhone 6 and it looks like there isn’t a 6 Plus and 6s Plus version.

The Smart Battery Case features an unfortunate hump at the back. Mophie’s Juice Pack design is a bit sleeker compared to Apple’s official accessory. Apple made sure that you can access all the buttons, cameras and microphones when you use the case.

Oh! And the case has passive antennas built into it for good measure, ensuring that the extra hardware strapped onto your phone doesn’t chip away at your cell performance.

While there’s no shortage of third-party battery cases out there already, Apple has something of home turf advantage here — namely, they can do whatever the heck they please with iOS to compliment their case in ways that no one else can match until/unless Apple opens up the APIs.