The 85W MagSafe 2 Power Adapter comes with a magnetic connector. So if someone happens to trip over it, the cable simply disconnects without your MacBook Pro falling to the ground. An LED indicator on the top of the connector lights up when the connection is established. Orange means the device is currently charging. Green means it is fully charged. The power adapter comes with a power cord for maximum cable length. The compact wall plug, also included, is perfect for travel. With its smart design, the power adapter is convenient for travel, as you can easily wind up the cable for compact storage. This power adapter charges the lithium-polymer battery whether the system is turned on, off, or in sleep mode. It also powers the device when you’re not using it on battery power. Compatible with the MacBook Pro with Retina display. Not sure if this power adapter is right for your Mac? More information to help you make the right choice. You’ll need to determine exactly which Mac model you have. If you’re using OS X Lion (10.7) or later, click “?" in the upper-left corner of the screen, then select “About This Mac" and click the “More Info…" button. Your Mac model and generation will be displayed. If you’re using an older version of OS X, enter your serial number here (in English) to determine which model you have: https://checkcoverage.apple.com/