The 20 way standard system master station is a surface/flush desk/wall mounted master station with stainless steel fascia and painted mild steel back boxes for systems of up to 20 outstations. The unit has an integral microphone and speaker and is fitted and LCD display, keyed enable switch, fault LED and large control button. The speaker and microphone volume are adjustable to suite the operating environment with a maximum output of 85dB for noisy areas. The unit is usually mounted in the control area and is used by operator to communicate with the system users in the event of an emergency. This unit is annotated in black, alternative annotation is available on request.