The round AO head brush is the right device to bring both heads and HMDs back into shape.
Conventional brushes with handles all have bristles on the side, if you want to get into your head from above or you just scratch the smokebox with the bristle-free tip on the floor.
Not so with the AO head brush: The handle-less design is perfect for guiding the bristle surface from above into the object to be cleaned and cleaning it over the entire surface.
The rough and robust brass bristles do a great job with stubborn tobacco residues and burnt-in molasses.