For use with the Pro-Medic Professional VIS-IR Ultrasonic Electric Power Toothbrush. 2 brush heads are included. Directions: align the bristle of the bristle head with the power button and then press the bristle head into the toothbrush. When you hear click sound, the bristle head is placed correctly in the toothbrush body. Replace your toothbrush head every three months to guard against nasty bacteria growth. When your brush"s bristles look worn, replace your brush head. • Set of 2 replacement heads • Use with Pro-Medic Professional Power Toothbrush models • Medium microfiber bristles • Designed for oscillation • Replace brush heads every 3 months