The RM-110: Extension unit with 10 keys with similar functions as IP-100RM remote microphone. IT holds up to 9 sets of RM-110, all connections can be linked. It is expandable to up to 105 function keys. The IR-100RM is a network remote microphone. It can be used for general broadcast and emergency broadcast. The microphone can receive messages from the server or other devices. It can also distribute these messages to select a zone or all zones.