Put in three pieces of AA1.5V batteries. The power consumption of this doorbell is

  low so the batteries can be used for 2 months,Install the electronic guest-saluting  

doorbell beside the door and turn the switch to music position, the electronic
 
guest-saluting doorbell will play music automaticly when people come by.  

Light control distance is 3-7 meters.
 
It is advised to use it in the places where there is enough light.