Wireless Remote DoorBell Button:

 

Working Power Includes Button Batteries
(Already includes for your convenient using)
Wireless Frequency 433MHz
Detecting Distant 50m-70m
Color Black & Silver, Looks Tiny & Great~
Size 45mm Diameter Round
(It is about the size of the Digoo M1Q lens.)
Convenient Function Stick one near your door, when some one press it.

 

 

Wireless Remote DoorBell Button.