Ultimate Mobility: up to 10 hours of laptop runtime

• Extend your internal laptop battery by up to 10 hours! (Actual runtime will vary with laptop model and power usage.)

• 2 USB ports allow you to charge digital devices at the same time! You can power any 5 volt device that has a USB interface. For instance, cell phones (iPhone), PDAs, Blackberry® devices, Pocket PCs, games, cameras and more!

• The PowerPad® is simple to use and requires no software.

• The PowerPad® works with most laptops. Its smart electronics automatically adjust for both 17V and 19V laptop configurations.

• The LCD display provides you detailed information on the battery performance. It displays:

• Rugged tough plastic casing provides durable protection.

• The light, thin design of the PowerPad® makes it easy to take anywhere.

• Capacity: maximum 130 Wh (15V, 8.6Ah)

• 2 USB Ports

• Dimensions: 10.6" x 8.2" x 0.6" (270 mm x 210 mm x 17 mm)

• Weight: 2.07 lbs (940 g)

• Charge Time: 85% of charge in 2.5 hours

• Smart Electronics automatically adjust for both 17V and 19V laptop configurations

• Limited Warranty: 1 year

130wH PowerPad external battery and 120w AC/DC Kensington adapter bundle for the Macbooks
This bundle will come with the external battery listed here and Kensington 120w AC/DC adapter.

You can use the Kensington AC/AC adapter both power and charge your Macbook Pro, Macbook, Macbook Air from any power source! And when your nowhere near power you can use the external battery to keep you running for additional hours! Oh, by the way, the external battery WILL charge your internal Macbook battery. No worries getting caught with a dead internal battery if you need to be truly detached!
Manufacture's product description for this external battery: