In the Enterprise/TOS crossover/mirror universe episode, Hoshi uses a TOS communications ear receiver... is this the @hms / Rodd version?
Also, is it missing the rubber earpiece?
Ouch, no tip it's no wonder she's just holding it up to her ear for the shots.
Yes It is a HMS that was used. It was sent with a rubber tip but who know what happens when it got to set.