Wireless Infrared Monitor Sensor Detector Entry Doorbell Door Bell Alarm Chime By Sistel Retail Packing Wireless door chime is great for retail store, shops, business, salons, front / back / side door, etc. Attach this infrared alarm anywhere you want and instantly know when someone crosses the beam. Working Range: Up to 100 meters / 328 feet between receiver and transmitter Receiver requires 2x AA batteries, transmitter requires 1x 9V battery (batteries not included) Material: Plastic. Melody: for Alice easy to install, can place everywhere