This is a really cool security device! It is a motion detector that produces an audible alert when it senses motion. Using the sensitivity adjustment feature it may be adjusted to exclude some smaller pets from being detected and producing an unwanted alert. Alert sounds include: Siren Barking dog Chime Chirping bird Music box Your own personal voice recording message up to 30 seconds (say whatever you want to say!) Possible uses for this announcer include: Home security (using the siren alert) Driveway, walkway or hallway alert Shopkeepers to alert when customer enters the front door (using the chime alert) Store to alert when a customer enters the department or shop Automatic greeter when a person enters a door or room Warehouses to alert when someone enters the back door / side door or enters restricted space General security (alert using a custom message that you record) Burglar alert (using siren, barking dog or a custom sound or message that you record to warn them) Back yard alert Vehicle alert when someone walks near A welcome alert A scary alert for a prank Prowler warning alert (side yard, back yard, garage, porch, etc.) Please note that this device is sold internationally, and it does have several prerecorded announcement alerts in Chinese but the instructions are in clear English and is very easy to set up.