Hydrosonic Pro brush head power: approx. 1404 filaments / diameter 0.152mm
Hydrosonic Pro brush head sensitive:  approx. 2184 filaments / diameter 0.127mm
Hydrosonic Pro brush head single: approx. 810 filaments / diameter 0.0889mm
Hydrosonic Black is White brush head carbon: approx. 1824 filaments (charcoal) / diameter 0.152mm inside / 0.127mm outside