Astronauts use a variety of microphones while on duty in space--handheld, attached to a headset, or installed inside a helmet. This is a basic press-to-talk handheld microphone transmitter-receiver that works like a walkie-talkie. It enabled astronauts to communicate easily with crewmates working elsewhere inside the Space Shuttle or to talk with Mission Control. It is not clear whether this particular device was used in training or in space.
NASA transferred it to the Museum with a variety of flown and unflown crew equipment when the Space Shuttle program ended in 2012.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.