Nutone NM100WH Intercom Master Station (White) System supports up to 15 remote stations when retrofitting a 4-wire system and 13 remote stations when retrofitting a 3-wire system, so you can connect with or check on family members as needed, to make everyone feel secure Set the system to automatically turn music on and off, at a predetermined time, so you can start or end your day with music at your convenience Built-in AM/FM radio tuner allows you to set 16 radio stations; use of the optional NC300WH 6-disc CD changer lets you enjoy music throughout the home, at a volume level you choose for the comfort of everyone Refer to the PDF attached below in Technical Specification for Manual