Oral-B Pro-Health Clinical Pro-Flex has flexing sides that adjust to the unique curves and contours of your teeth, including gum line, for a superior clean vs. an 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 gum line, for a superior clean vs. and ordinary brush with regular use. Flexing Sides! One Superior clean vs. an ordinary manual brush.*with regular use Gentle on gums. Individual flexing sides.