This is simple hack that allows users to activate an electric toothbrush without having to press the on/off button. This modification adds a reed switch to the main board of the toothbrush so it can be activated through close contact with a magnet. It’s suitable for users with limited finger dexterity or one handed users.
Place a piece of magnet close to the reed location outside of the casing to activate the on/off switch. Users can also attach a magnet close to a ring for one handed usage.
I think that they have changed the model of the toothbrush you have linked, and now to take it apart instead of it being threaded it has two tabs (on the front and back) that need to be pried open. I learned this the hard way so hopefully this helps someone else 🙂