Apple is now selling its Smart Battery Case for $99. From the product page at apple.com: "Charge your iPhone and battery case simultaneously for increased talk time up to 25 hours, Internet use up to 18 hours on LTE, and even longer audio and video playback. With the Smart Battery Case on, the intelligent battery status is displayed on the iPhone Lock screen and in Notification Center, so you know exactly how much charge you have left." This device is not available for the iPhone 6s Plus, only for the 6s. Also, Apple has not shared details on the capacity of the device in mAh. A popular tech site reports that "users of last year's 4.7-inch iPhone 6 model may be able to use the new case due to its design similarities to the iPhone 6s." Apparently this is not officially guaranteed by Apple. Update: According to The Verge, "The Apple Smart Battery Case has a 1,877mAh battery pack." You can find The Verge's fairly thorough review here, and I've included the video version immediately below.