Bristles : blue bristles will fade when a replacement is needed, usually three months. HEALTH & SAFETY STANDARD: OEHHA Prop 65 approved Brushmo toothbrush heads are made at the sustainable health and safety standard of oral hygiene technology. 8 +2 VALUE PACK INCLUDES: 8 Brushmo Plaque Removal Replacement heads, 1 Brushmo Sensitive Replacement head, and 1 Brushmo Compact Size Replacement head. WIDE COMPATIBILITY: Snap-on system fits 2 Series Plaque Control, 3 Series Gum Health, DiamondClean, EasyClean, FlexCare, FlexCare+, FlexCare Platinum. HealthyWhite and HydroClean Brush Handles. (Not Compatible with Essence +). EFFECTIVE GUM HEALTH IMPROVE: Brushmo standard toothbrush heads are proven to reduce gingivitis up to 7x better than a manual toothbrush.