Oral-B Pro Cross Action toothbrush heads have X-shaped bristles that remove plaque from areas that other bristles cannot reach. The round head of these brushes hugs the tooth, reaching even between the teeth. Cross Action means the bristles are arranged at an angle of 16°, which further enhances the cleaning performance. These brushes have indicator bristles that change color to let you know when it's time to change the brush. The package contains four toothbrush heads.