ECONOMICAL SMART SIREN: many features packed into one compact loud siren, just a little over 3 inches wide!MULTI-FUNCTION!Use as a panic alarm, as a home intrusion siren, have it activate if a door or lid is left open too long, and use it as an alarm for water leaks* and high or low temperature and humidity* or all of the above!*Additional YoLink devices required, not included.WHY PAY A MONTHLY FEE if you can secure it for free?See below for the many ways your siren can respond and for you to be notified of off-normal events, from a high-temp alarm, to motion detected in the back yard, or a garage door left open too long (other YoLink devices required, not included)DEVICE-TO-DEVICE PAIRING allows for two or more (up to 128!)devices to be paired together, in such a way they will perform their action even without WiFi, internet, and power!(Battery-powered or backed-up devices).Perfect for security and other critical functions: pair your water leak sensors to your Siren Alarm, and to your Smart Motorized Valve.EVEN BETTER with a SirenFob!Pair one or more siren products to your SirenFob, then pair one or more alarm products (such as door, motion, vibration sensors - ideal for vehicles, RVs, and other mobile applications or where internet is not available.*Additional YoLink devices required, not included.Search for B0BRCX6HVKSTART SMART!A YoLink hub is required for full functionality, including for the app to work, to check battery level, etc, but your hub is compatible with a growing family of smart products for home and business!Search for B0BJJZH511 for a starter kit with YoLink Hub or search B09FSS95G9 for a SpeakerHub (our audio, talking hub).BATTERIES ARE INCLUDED!LOOKING FOR SOMETHING FOR OUTSIDE?Search B092QR82P1, B09V2DXPPW, B0BWYLT3JB, B0BZHPQ1PKWANT TO USE YOUR OWN STROBE, BELL, BUZZER, ETC? Search for B0BWYLWWV6