This is a secondary modular bay replacement battery for Dell laptops. To use this battery, remove the CD drive from your laptop chassis and then plug in this secondary battery in its place. With 2 batteries now in your laptop, you have almost doubled your battery run time! The superior South Korean cells inside the battery cartridge will provide longer run times between charges as well as a longer service life than cheaper batteries. In addition, Li-ion batteries are not subject to the memory effect common with older battery technology. This means you can recharge your laptop any time without diminishing your battery capacity. This battery will supply about 2 hours of run time in addition to the run time provided by your standard primary battery and is 100% compatible with your Dell notebook computer. The battery is individually tested before shipment and backed by 30 day complete satisfaction guarantee and a 2 Year warranty.