The MagSafe Battery Pack attaches with a snap. Its compact, intuitive design makes on-the-go charging easy. And its perfectly aligned magnets keep it attached to your Iphone providing safe and reliable wireless charging. The MagSafe Battery Pack can charge even faster when coupled with a 27W or higher charger, like those that ship with MacBook. And when you're in need of a wireless charger, just plug in a Lightning cable for up to 15W of wireless charging.