Oral-B Pro-Health Clinical Pro-Flex has flexing sides that adjust to the unique curves and contours of your teeth, including gumline, for a superior clean vs. and ordinary brush*. Because of its flexibility, it is gentle on gums too.; Flexing sides adjust to the unique curves and contours of your teeth, including gumline, for a superior clean vs. and ordinary brush*.*with regular use.; Flexing Sides! One Superior Clean* with regular use vs. ordinary manual brush.; Gentle on gums.; Individual Flexing Sides.