The Brio ProClean replacement brush heads are the only electric toothbrush head equipped with DuPont anti-bacterial bristles! DuPont anti-bacterial bristles use antimicrobial filaments which help to naturally eliminate bacteria in your mouth while you brush which benefits your entire body, not just your mouth! The filaments also help to keep the brush clean between brushings. The smaller size guides the brush into spaces that are harder to reach and the concentrated bristles provide a vigorous clean but are still gentle on your gums and enamel. All Brio brush heads are designed to fit with any Brio toothbrush. Brush heads should be replaced every 3 months or sooner depending on wear. If you are wearing them out much sooner than that, you are probably brushing too hard, so take it easy. Keep the heads in their hygienic resealable package until they are ready for use.