Apple Apple 85W MagSafe 2 Power Adapter (for MacBook Pro with Retina display)

See this article for more details about choosing the right one. Knowing which specific Mac model you have is important. If you are running OS X Lion (10.7) or later, go to the “” menu at the top left of your screen, choose “About this Mac” then click the “More Info...” button. Your Mac model and generation will be displayed. If you are running an earlier version of OS X, you can enter your serial number here to find out which model you have. This power adapter recharges the lithium polymer battery while the system is off, on or in sleep mode. It also powers the system if you choose to operate without a battery. Compatible with MacBook Pro with Retina display.