The iO 4 electric toothbrush is equipped with Oral-B’s best technology, which combines a dentist-inspired round brush head with micro-vibrating bristles for a professional, cleansing and clean feeling at home. The smart pressure sensor helps you not to brush either too hard or too soft, so you protect your gums better. Gum Guard warns you when you brush too hard. Replace your Oral-B iO Series brush head every 3 months for best results.