Features: * REAL-TIME TEMPERATURE DISPLAY: It will automatically detects the ambient temperature when plug in the receiver,and the real-time temperature will be displayed. * 656FT/200M LONG WIRELESS RANGEE: 1 plug-in receiver included; will not interfere with other equipment in your home or those of your neighbors; ensures you will never miss a visitor, even if you are a few rooms away or on another floor. * 45 CHIMES TO CHOOSE FROM: Delivers rich and crisp sound; 4 adjustable volume levels with mute function. press Next button to easily choose from 45 melodies. * HIGH PERFORMANCE TRANSMITTER: Ultra-low power consumption. Dustproof and waterproof; withstands various harsh weather conditions. * SIMPLE SET UP & USING: Just plug the receiver into a socket, and fix the transmitter on a wall with the accessories provided. Remembers your last melody and volume level after a power outage; no need to reset to your previous settings. * MULTI-USE: It is fit for home, apartment, classroom, office, villas and more. And it can be a paging device for the elderly, can signal for care when they need it most. *Self-powered No Battery Required: By pressing the outdoor doorbell, mechanical energy is converted into electrical energy when pressing. Specifications: Item Type: Wireless Doorbell. Color: White,Black(Optional). Plug: US/EU. Plug-in Receiver: Function: Temperature Display. Working Voltage: 80-260V. Working Current: 0.1ma. Working Frequency: 433MHz. Selectable Ringtone: 45 Melodies. Volume Rangee: 4 Levels with Mute Function. Decoding Format: 1527. Receive Rangee: Up to 200M/656FT. Size: Approx. 78x72x20mm(HxWxThickness). Transmitter: Waterproof: Ordinary waterproof. Working Voltage: DC 12V/23A. Working Current <25ma. Power Supply: 12V/23A Battery(Not Included battery). Size: Approx. 68x46x18mm(HxWxThickness). Note: Battery is necessary, but self-powered function can make the battery last longer. Package Included: 2pcs: 1 x Plug-in Receiver + 1 x Transmitter 3pcs: 2 x Plug-in Receiver + 1 x Transmitter