85 Watt MagSafe 2 Power Supply from Apple (for MacBook Pro with Retina Display)
The 85 Watt MagSafe 2 power supply is equipped with a magnetic power connector, so when someone stumbles on a cable, it disconnects without pulling a MacBook Pro. It also helps to protect the cables from damage or wear. In addition, the magnetic power connector makes it easy and fast to connect the plug to your computer.
When connected, the LED on the top of the power connector lights up. The yellow LED indicates the notebook is charging, and the green indicates that the computer is fully charged. The power supply is supplied with a power cable that maximizes the cable length, while the wall plug (also included) is perfect for travel.

The power adapter is a great travel companion - thanks to well thought out design, you can carefully wrap the DC cord around it so that it does not mess up during storage.
With the AC adapter, you can charge the lithium polymer battery when the computer is off, on, or in sleep mode. It also powers the computer while operating without batteries.