The SoFresh flossing toothbrush "dual action" bristles are a technological breakthrough. Composed of both short and long bristles this unique design allows the brush to properly clean the sides and top surfaces of the teeth and at the same time clean deep between the teeth and below the gum line. Each short bristle is rounded and polished to provide a smooth, gentle cleaning action. Each long bristle is meticulously machined to a fine point allowing it to gently clean where no other brush can go. In addition, the special "soft grip" oversized handle allows effortless and precise brushing. SoFresh flossing toothbrush is so well designed that it only comes in a "soft" bristle configuration. Why? Because as dentist we know the firmer the bristles the more abrasive the brush is to the teeth. We call this phenomena "tooth brush abrasion" and it can laterally wear grooves in your teeth at the gum line. The SoFresh flossing toothbrush's soft bristles are designed to prevent "tooth brush abrasion" while providing maximum cleaning action. Remember all toothbrushes should be replaced every three to four months to assure maximum cleaning action.