A set of 4 x natural-bristled hard replacement toothbrush heads Quick and easy to change toothbrush heads The low and high bristles effectively clean your back teeth (as well as everywhere else) Reduce unnecessary waste by replacing the toothbrush head Dentists advise you change your toothbrush (heads) every 3 months Save money - replaceable heads are cheaper than replacing the whole toothbrush Free from PAHs, phthalates &heavy metal Bristles are made from boar hair. The animal is not hurt in the process - it is shorn, like a sheep.