No Guessing: The toothbrush replacement head has special bristles, which are Blue-colored and will fade to white after brush for 3 months, reminder you for replacement. Advanced Bristle Planting Technology: Ofashu toothbrush replacement brush heads adopt advanced bristle planting technology. No need to worry about the bristles of the brush head falling off. Superior High-efficiency Clean: Ofashu standard toothbrush heads can remove up to 10x more plaque along the gum line and in between teeth. Unique design: streamlined section of the bristles, which better fits the shape of the teeth, and effectively cleans the gaps and difficult-to-reach corners of the teeth. Compatible With Snap-on Philips Sonicare: Ofashu electric replacement brush heads compatible with C3 Premium Plaque Control 2 Series, 3 Series gum health, DiamondClean Smart, EasyClean, Essence+, FlexCare, FlexCare+, HealthyWhite+, PowerUp, ProtectiveClean 4100 5100 6100 9900 7500 hx3220b hx6730 hx 6250 hx9044 C3 G2 G3 W W3.