Since 1965 Lenmar has been building award winning, high quality power related products. Lenmar personally manages the excellence of our products through every aspect from design to production. The Lenmar ChugPlug is a patented external power pack that seamlessly integrates with Apple"s MagSafe Power Adapter to power and charge MacBook"s anywhere. The ChugPlug is compatible with all 45W and 60W MacBook"s: all models of the MacBook Air, and 13inch MacBook Pro"s. The ChugPlug has a 4000mAh internal battery. This battery adds up to 4 hours of additional battery life to the MacBook Air and up to 3 additional hours to a MacBook Pro. Designed in California by Lenmar, the ChugPlug belongs in your Apple family. Simply connect the ChugPlug to your existing MagSafe Power Adapter for a seamless, secure, integrated fit. Bring the ChugPlug with you to the airport, to the office, or use the portable device in the comfort of your own home - the opportunities are endless once you stop relying on the nearest AC Power outlet to keep your MacBook running. The ChugPlug is a unique, one of a kind product.