The iO 4 White electric toothbrush features Oral-B's best technology, combining a dentist-inspired round brush head with micro-vibrating bristles for a professional purifying clean feel at home. The Smart Pressure Sensor helps prevent you from brushing too hard or too softly to protect your gums better. Gum Guard alerts you to time spent brushing with too much pressure. Replace your Oral-B iO toothbrush head every 3 months for the best results.