Larger battery for extended runtime.
Cleans intelligently in straight lines back and forth to thoroughly clean your floors while navigating around furniture.iRobot Roomba i4 Vacuum Cleaning Robot I415920 - Black Black Condition: Refurbished Dimensions: 3.0 inches (L) Weight: 8. iRobot Roomba i4 Vacuum Cleaning Robot I415920 - Black iRobot Roomba i4 Vacuum Cleaning Robot I415920 - Black (Refurbished) 20% LARGER BATTERY ? Refurbished iRobot Roomba i4 Vacuum Cleaning Robot I415920 - Black Black.