Keep in mind this isn't Apple's first battery case - just the first MagSafe one. And it doesn't come with any other special features, either. For instance, the iPhone 11 battery cases had a physical camera shortcut button. Still, the new one works like the MagSafe wireless charger, so you could use it to top up your AirPods or other devices that support Qi wireless charging.
According to Apple, the MagSafe Battery Pack charges devices with up to 5W of power, so it's not exactly the speediest option. It also requires iOS 14.7 - a software update that’s not out available. However, Apple’s website is surfacing delivery times for the battery pack for between 22 July and 27 July 2021, so perhaps the update will arrive before that delivery window.
The MagSafe Battery Pack costs $99 in the US. You can order one right now from Apple’s website. It works with all four iPhones in Apple's latest lineup, too: the iPhone 12, iPhone 12 Mini, iPhone 12 Pro, and iPhone 12 Pro Max; the iPhone 13, iPhone 13 Mini, iPhone 13 Pro, and iPhone 13 Pro Max.
Apple also sells a MagSafe wallet that can attach magnetically onto the back of your iPhone 12/13. For more MagSafe accessories, see our listings: