3500mAh Replacement NI-MH Battery for iRobot Discovery Series, iRobot Dirt Dog&reg; Models, iRobot Create Models, iRobot Roomba FloorVac 400 Series Models Replacement NI-MH Battery for iRobot Discovery Series, iRobot Dirt Dog&reg; Models, iRobot Create Models, iRobot Roomba FloorVac 400 Series Models