UpStart Battery iRobot Roomba 4210 Vacuum Replacement Battery - 14.4V. 3300mAh. NIMH.

Buying a battery or charger is not the most exciting purchase you will
ever make. We know that. But the music you want to listen to, the
pictures you want to take, the work you need to do, the people you want
to call, the movies you want to film.... those are exciting - and
that's why you need premium batteries and chargers.
Buy a brand you can trust. Choose UpStart Battery.

Product Specifications Brand: UpStart Battery Chemistry: NIMH Output
Volts: 14.4v Capacity: 3300mAh Brand: Color: Yellow Condition: New
This Product works in or replaces
the following OEM model numbers:

iRobot Roomba Original Series, 400 Series, 4220 Series, 4230 Series,
4240 Series, 4250 Series, 4260 Series 4905 Series, Discovery Series and
iRobot Dirt Dog.