The FlexFit Tech brush features soft rubber links for optimal interdental cleaning and excellent teeth protection, along with an innovative 5° design for deep cleaning below the gum line. It includes DuPont™ and self-developed bristles for a comfortable cleaning experience, a delicate tongue cleaner for fresher breath, and is compatible with all Oclean adult toothbrushes, recommended to be replaced every 2-3 months. Bristle firmness: Firm