Oral-B iO Ultimate Clean Replacement Brush Heads, 4 Pack[Replacement brush that realizes iO's plaque removal power] The Ultimate Clean replacement brush for the iO series features a precisely designed internal structure that enables iO's unique centrifugal micromotion. Only genuine products with a brand guarantee can maximize plaque removal power. [Maintain plaque removal power by replacing the brush properly] Replace the replacement brush approximately every three months. If the bristles spread apart,