Induction method: infrared sensor triggered 3 modes: Voice Alarm Music,at "Voice" mode: Human voice,dingdong,ninhao, ; at "Alarm"mode: keeps you aware of intruders; at "Music" mode: just as a doorbell,with 32 music to welcome your guests Detection Angle: Horizontal Angle of 110 degrees, vertical Angle of 15 degrees Volume: 4 levels adjustable (Can' adjust volume at alarm mode) Power supply: DC 9-15V adaptor(not included) or 3 pieces of AAA battery(battery not included) Chemicals of concern: None Type:Doorbell Detector Alarm Colour:As Shown Material:Plastic Package Contents: 1 * Doorbell Detector Alarm Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.