The Philips Sonicate optimal plaque Control brush head features a concave trim profile specifically designed to target tooth-decaying plaque by hugging teeth and offering better conformity and surface-area coverage. Compatible with all click-on Sonicate models, these replacement brush heads remove up to 6x more plaque than a manual toothbrush. Use with a Philips Sonicate brush Sync(TM) compatible handle (Diamond Clean Smart or protective Clean) to unlock Smart features brush Sync mode-pairing triggers your handle to select optimal mode and intensity level for exceptional plaque removal (certain models only) brush Sync replacement technology tracks how often and how hard you brush and will notify you when it is time to replace your brush head. Also, reminder bristles fade to let you know when its time for replacement. Replace your brush head every 3 months as recommended by the American Dental Association. A fresh brush head every 3 months maximizes the effectiveness of Philips unique Sonicate technology.