The Sonicare HX9042/65 is the deepest cleaning and most advanced brush head. It is designed to work with all click-on sonicare models. These replacement brush heads have flexing sides that contour to your teeth and gums for 4X more surface contact and our deepest clean. Smart mode-pairing triggers your handle to select optimal mode and intensity level for exceptional plaque removal. Smart brush head replacement technology tracks how often and how hard you brush and will notify you when it is time to replace your brush head.