Eco Warehouse Electric Bamboo ToothbrushTo make the handle waterproof, because if it isn't then the electronics will fail, it is made of polypropylene with a bamboo look. Great design and it reduces your impact on the environment. With compostable bamboo heads and charcoal infused PBT bristles, its a true revolution for those who want a more powerful teeth clean. PBT (a type of polyester) bristles are stronger than your regular Nylon bristles and therefore last longer (3 4 months). Each box