Got an iPhone 12 or iPhone 12 Pro and you always seem to be running out of battery? Apple has a new accessory to help you out: the MagSafe Battery Pack is on sale for $99. According to the Apple store online, it won’t ship until next week.

As the name of the product implies, the battery connects to the iPhone 12 via MagSafe, the magnetic connector on the back of the phone. According to the product description on Apple’s website, the MagSafe Battery Pack “automatically charges, so there’s no need to turn it on or off.” However, you can’t use two MagSafe products at once, so if you’re using the wallet, you’ll need to swap it out

Apple does not list the capacity of the MagSafe Battery Pack—though the image says 1460mAh with a 7.62 voltage and Wh rating of 11.13—and it does not come with the items you need to charge the battery pack itself: a USB-C to Lightning Cable and a power adapter. Apple recommends using a 20W or higher adapter; you can use a lower-rated adapter, but it will take longer to charge. Apple’s 20W power adapter and a 1-meter USB-C to Lightning cable are $19 each.

According to an Apple support document, the MagSafe Battery Pack needs to be fully charged before using it, and it has status lights to indicate when the pack is charging and fully charged. With just the pack attached to the iPhone, it charges at a rate of 5W. When the pack is connected to the power adapter and an iPhone at the same time, the rate goes up to 15W.

The MagSafe Battery Pack requires iOS 14.7, which isn’t yet available to the general public, but the release candidate was just made available, so look for it soon. When using the MagSafe Battery Pack, you can check the charging status in the Batteries widget, which you can add to your Home screen or see in the Today View.

The support document also notes that if you use a leather iPhone case, using the MagSafe Battery Pack could leave an imprint. Apple says this is “normal” and if this raises a concern, you should consider a non-leather case instead.