Amazon.com: HQRP 2200mAh Battery Works with iRobot Mint 4200, Mint 4205, Braava 320, Braava 321, 4408927 Automatic GPHC152M07 Ultra High Capacity [Robotic Vacuum Cleaner] : Home & Kitchen
Powerextra 3.0Ah 7.2V Replacement Battery for iRobot Braava 320/321 & Mint 4200/4205 - Walmart.com