TOPCHANCES 14.4V NI-MH Replacement Battery for iRobot Roomba 500 510 530 570 580 550 532 535 540 560 562 610 R3 High capacity extended 14.4V 3500mAh Ni-MH rechargeable battery pack. Uses the highest quality cells, safe with rapid-charge technology while providing overcharge and overdischarge protection to increase the life of the battery. This replacement battery is designed for for iRobot Roomba 500 series vacumm cleaner, It is a kind of Ni-MH Rechargeable battery, you can carry it anywhere anytime, convenient to use. And it's has no memory effect. Can be charged or discharged as needed without loss of capacity. Uses the highest quality cells, safe with rapid-charge technology while providing overcharge and overdischarge protection to increase the life of the battery . Gurantee : All batteryies 30-day money back and a 12-month limited guarantee defects from date of purchase, and 24 hours' friendly customer service!!