Oral-B iO Ultimate Clean replacement brush heads help remove plaque effectively, providing a deep clean for teeth and along the gum line. These replacement heads are designed exclusively for Oral-B iO electric toothbrushes. Their round shape, inspired by dental tools, combines with gentle micro-vibrations to provide a deep clean sensation every day. The bristles, of varying lengths and their arrangement, allow them to surround teeth and reach deeper into the spaces between them and along the gum line. The bristles feature indicator technology that gradually changes color, helping you identify when it's time to replace the brush head. To maintain adequate cleaning performance, Oral-B recommends replacement every 3 months, or sooner if the bristles are worn. The package contains 4 brush heads, providing refills for up to one year, considering the recommended replacement every three months.