It's a wireless doorbell which is small and exquisite.
There is a built-in battery which can work for one year.
The transmit distance of signal is 100 meters long.
The doorbell must work together with Golden Security System,such as:GS-S2W GS-G90B GS-S1 GS-G90B Plus.
Easy to fix it on your front door and it's convenient to add into the alarm systems.