Bunker Headset Original Rubber

A rusty specimen of an original Fhf 39d on the market by ‘Kpemig’ showing there is a full filling of the earpads which is new to me.

Unlike the earpads for the Dfh.b (Panzer headset in collector’s term) which are hollow inside, these foam like material wrapped by a thin layer of rubber skin may be for wearer’s comfort for long term wearing (so do the Panzer crew). Similar to the soft ear cushions of  the modern headsets.

Or for improvement of hearing protection when in a closed environment (but there is Coastal Artillery headset for big guns and Falk headsets for FF33 with a single earpiece already).

Any information is welcome.