Vertex MH-89A4B Earpiece Microphone Single-Wire Surveillance Kit
Model Number:  MH-89A4B
Remotely control the radio with a single-wire surveillance earpiece microphone. This device features an inline microphone and Push-to-Talk (PTT) button for one hand operations while discreetly listening to the audio through the integrated earpiece. The earpiece features an over the ear speaker for added comfort.