Long distance 315MHz/433MHz two receivers wireless doorbell for apartments

Long distance 315MHz/433MHz two receivers wireless doorbell for apartments   Specification:  1) ABS material housing
2) Working frequency: 315MHz / 433MHz
3) Detection range: 50-80 meters in open air
4) Built-in 38 melody chimes
5) Adjustable volume
6) Power: - Transmitter was powered by 1 x 23A 12V battery (Not included)
7) Receiver voltage: AC 220V (2-flat-pin plug)
8) LED Indicator: press the send button, LED indicator light will flash, emitter work and the receiver receive the order and then send out the beautiful music reminded you the VIP visit, the blue-ray LED of the receiver will regular flash along with the music.
9) Music source: 38 songs supply for choice, Use the External button "up/down" to finish 10) The function of volume regulate: high, middle, low three volume can choice, use the External switch (or button) to finish   Feature: 1)It's a great tool to warn you when guest or thief coming 
2)Effective alarming detecting distance is 6 - 10m. 
3) Super long receiving distance. 
4) 16 melodies for selection, you can select your favorite. 
5) Environment friendly energy saving system. 
6) Infrared sensor principle design 
7) Installed in the doorway at the top or the wall , adjust the probe angle to the appropriate location when guests access to its detection range , the doorbell indoor automatically send sweet music prompted the master
  Product Display:   You can install the doorbell in locations, such as doorway, back yard, or bedroom, you will never miss your guests.