BWireless Infrared Monitor Alarm Entry Doorbell Chime--White ReviewbP PP Wireless Infrared Monitor Alarm Entry Doorbell Chime--White PWireless installation, just place the sensor at the entrancePInfrared sensor detects motion and sends a signal to the receiverPReceiver requires 2x AA batteries, transmitter requires 1x 9V batteryPSend audible chime sound, alerting you that somebody is approachingPMaterial: Plastic.