This is a brand new Lenovo IdeaPad N580 N581 N585 N586 battery.
This battery is rated at 5200 mAh or 58 Whr. This is the highest rating available for a 6 cell battery pack. The higher the mAh rating, the longer your battery will run before it needs to be recharged again. There are no compatibility issues if your existing battery is rated at 4400 or 4800 mAh or a lower Whr. Simply put, more is better. And yes, this battery is probably better than your original!
All our products carry a full 2 Year warranty and every battery is charged and tested before it ships. We provide a 30 day money back guarantee if you are not completely satisfied. We are so confident in the quality of our batteries, we will pay for any and all shipping expenses if our product fails to perform in the first 30 days you have our battery, even if it is not our fault.