The Philips Sonicare SimplyClean brush heads are designed to work with all Sonicare click-on toothbrush handles for an effective clean. The SimplyClean brush heads have Reminder Bristles that fade to let you know when it's 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 Sonicare technology.