8-Pack is a 1 Year Supply For 2 People - Color Coded Rings to Remind 2 Users to Change Brush Head Every Season Features +29% More Cleaning Bristles and New Trim Pattern for Improved Tooth Cupping Dentists recommend changing your brush head every 3 months Indicator bristles fade half-way to signal it is time to change your brush head. Fits: Oral-B Professional Care Smart Series, Triumph, Professional Care Series, Vitality, Precision Clean Fits: Oral-B Dual Clean, Floss Action, ProWhite, Pro-Health Battery Powered, AdvancePower Series