Wireless set includes door push and Battery operated chime unit - Very easy and super fast setup with no wires. . Front facing SMD LED flashes when the door bell is pushed, ideal for anyone who may be hearing impaired!. Wireless means the receiver can be placed anywhere around the house. Approx 100M range (unobstructed), choice of 20 melodies, 3 level volume control. 1 x 12 volt battery (Type is called MN21, A23 or LRV08 battery) for the door push is included, Door chime requires 3 x AA Batteries (not included).