Small gap between toothbrush replacement heads and handle for powerful vibration and less noise. These replacement brush heads are equipped with specially designed bristles that contour to your teeth to provide effective cleaning action while remaining gentle on your teeth & gums. Reminder bristles will fade a replacement is needed, usually three months. Soft End-rounded Bristles protect both your teeth and gum, and bring you a comfortable brushing experience. Toothbrush heads for Aquasonic Duo and Home Dental Center.