iRobot Roomba Series 500, 600, 700, 800, and R3 Battery
APS battery for iRobot Roomba 500, 600, 700 series (Original)
Amazon.com: iRobot Roomba Authentic Replacement Parts - XLife Extended Life Battery - Compatible with Roomba 400 600 700 800 Series Robots : Home & Kitchen
Replacement Battery for Roomba 500 600 700 Series APS Battery 555 595 620 630 650 660 790" - Walmart.com