This is a Genuine Apple 85W MagSafe 2 Power Adapter model MD506LL/A. Use an extra adapter for home or work. The Apple 85W MagSafe 2 Power Adapter is made specifically for your MacBook Pro with Retina display. It’s held in place magnetically, so if someone should trip over it, the cord disconnects harmlessly and your notebook stays put safely. 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.