Bamboo Handle, 100% Plant-Based Castor Bean Oil Bristles. A metal staple is used to clamp the plant-based bristles into the brush, keeping them from falling out when you're brushing your chiclets! It's a normal part of a toothbrush, and even plastic ones have staples in them too! When you're ready to replace your toothbrush head (dentists suggest every 3 months), simply replace it with a new head and keep the handle. To dispose of the used head, you can also remove the bristles from the head using a pair of pliers, which will also remove the staple, and compost the bamboo. The bristles are not yet biodegradable but fear not, the etee team is working on a solution!