The Six Zone Wireless Door Bell System is perfect for offices where multiple services are required, Ideal for office ,hospital, restaurant and etc where services are needed with six zones Adopt energy-saving circuit. Three AA Battery Included , Load three AA LR6 batteries on receiver for long use. Two sounds for option. Adopt energy-saving circuit, batteries for transmitters can work for one year, batteries for receiver can work for three months Wireless service this device, a dedicated elevator intercom, hotels dedicated doorbell