Telephone Handset used for fire alarm intercom system.Compatible with YF-1 Fire Alarm Panel Range and other fire intercom devices. TPFSTHS001 Yun Yang Conventional Fire Alarm Control Panel YF-1 5 Zone Yun Yang Conventional Fire Alarm Control Panel YF-1 20 Zone Yun Yang Conventional Fire Alarm Control Panel YF-1 15 Zone Yun Yang Conventional Fire Alarm Control Panel YF-1 10 Zone