HQRP 2200mAh Extended Battery for Mint 4205, Braava 320, Braava 321, 4408927 iRobot Automatic Hard Floor Cleaner Robotic Vacuum + Coaster HQRP&reg; Rechargeable Battery plus HQRP&reg; Coaster; Battery Voltage: 7.2V; Capacity: 2200 mAh; Ni-Mh; 100% compatible with Original Battery; 200 Days warranty!