Fratures:

• The 85 Watt MagSafe Power Adapter features a magnetic DC connector that ensures your power cable will disconnect if it experiences undue strain and helps prevent fraying or weakening of the cables over time.
• When the connection is secure, an LED located at the head of the DC connector will light up; an amber light lets you know that your portable is charging, while a green light tells you that you have a full charge. 
• Designed to be the perfect travelling companion, the adapter has a clever design that allows the DC cable to be wound neatly around itself for easy cable storage.
• 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 15- or 17-inch MacBook Pro.