1.Announcing the guest has arrived with the beautiful melodies. The sound is quite loud,charming and ear-catching presetting many sorts of sound for selections. 2.open the batlery lid of the doorbell,install the batteres,the batteries which you are invited would be better ones,Two/Three NO.5 batteries,"AA size",it is shortes in life and easier to seep the electrolytes for using the bad ones.After using for a long period of time,please change the batteries which are out of normal uses. 3.The doorbell is with long wire,you can install it at suitable position as like.Supply Voltage(Vdd):3V Quiescent Supply Current(Iccq):≤1.2μA Alarm Supply Current(Iccd):≤145mA Decibel(dB): 30CM≥107dB;60CM≥101dB;100CM≥99dB | 
