Entrance Alert Set for All Door Types Entry Alert System For Commercial, Industrial, Retail, Convenience Stores, Doorbell Entrance Alarm Wireless PIR Sensor Picks Up Motion & Transmits Signal To Plug In Receiver Up To 1000' Away Easy To Install Wireless Door Entry Alert. Transmitter Operates On AA Batteries. Chime Plugs-In. Ability To Narrow The PIR Field Of Detection So You Don't Pick Up Customers You Don't Want To 4 Selectable "Ding-Dong" Tunes. Adjustable Volume Control