Water-Resistant Wireless Doorbell Door Chime with Push Button, about 100M/330Ft, 36 Chimes, 4 Volume Levels, 2 Receivers Wireless battery operated doorbell system of 1 transmitter and 2 receivers. Both the Transmitter and Receiver are battery operated. Creative, waterproof design. Prevent rainwater infiltration which prolong service life. 36 chimes included: Pick one you like from modern to old fashioned chimes. Loud enough to hear at any of the 4 levels of volume and low enough so it won't disturb any sleeping children.