SadoTech Wireless Passive Infrared Dual (2) Motion Sensor Doorbell, Short Reset Delay (1-5 sec), LED lights, 25-feet Sensor Range with 50+ Chimes - Unique doorbell with motion sensor detector that triggers the doorbell main unit. Creative uses such as alerting when someone approaches the door or driveway, when your mailbox is opened, alerts when a window or door is opened, alerts when a perimeter is breached. Can be used as a simple alert unit instead of investing in costly security systems - Detection time delay in between motion sensor alerts is configurable from 15 seconds to 30 seconds. Operating range of over 500 feet (between sensor and main chime unit). Receiver easily plugs into an electrical outlet (no batteries required) - Note: Manual is attached above the Product Description for SetUp and Trouble Shooting Tips. Motion sensor range area is about 12meters (40 feet) area at an angle of 110 degrees - Over 50+ different ring tones. Four levels of adjustable volume from 25db to 110db. This item is a highly configurable and technical item. It's a motion sensor and can be prone to false alarms due to incorrect placement and configuration of the product - Includes 1 plugin receiver unit and 1 motion sensor, anchors, screws, and battery for motion sensor. (This unit is NOT compatible with Starpoint L Series)