eames la fonda naugahyde upholstered chair drilled holes  

hi all,
based on my observation.
the straight fiberglass ones do not have drilled holes on the shells.
the upholstered ones that have the threaded holes embedded in the shell also do not have drilled holes.
the upholstered ones that have glued on shock mounts have drilled holes
but then i have also seen the upholstered ones with glued on shock mounts not having the drilled holes.
were those factory drilled holes? i suppose they were for ventilation/breathing? if so, how come some of them with glued on shock mounts do not have them?
thanks,
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