Мелодия дверной звонок

Musia doorbell 1.open the doorbell's battery cover when using. And install two NO.5AA sized alkaline batteries.(it will damage the battery clip to ulictize the common batteries for easily seeping the electrolyte.That causes the batteries'lives to be shortened. )The electricity losses are extremely low. That alkline batteries can be used for one year. (Counting it by twenty times a day) 2.The button is assembled in the appropriate position at the gate and you connect the wire for the operations immediately.(The cord can't be parelleled with the clectric fire line or assmbled into the same wire groove to avai d the mis-touches. 3.After using it for a period of time,please discard the old batteries for its innormal operation.