Model Sws51, 3-Pack; X-Sense Smart Water Leak Detector, Wi-Fi, Single Pack. Note: The alarm cannot be directly added to the app and a base station is required Expand Your Smart Home Your Way: The SWS51 is an accessory for SWS54 water detector kit (compatible with FS31 smoke alarm kit); long transmission distance of 1,700 ft (500 m); simply press the test/silence/pair button to connect the sensor to the base station and add up to 50 devices Real-Time Notifications: When a water leak is detected, a push alert will be sent to your phone, so you?ll be alerted quickly even while you are not at home; you can share the device with your family members so they can also check the device status anytime, anywhere (Note: The SWS51 water leak sensor needs to be paired with the X-Sense SBS50 base station to be used.) Know from Anywhere: Once triggered, the water leak sensor and base station will sound simultaneously at a volume of up to 110 dB ? loud enough for everybody to hear; simply mute the alarm via the app or push the silence button on the base station or water leak sensor High Sensitivity: The SWS51 water leak detector is equipped with 2 top sensor probes and 4 bottom sensor probes to detect water leaks and floods; provides an early warning of water damage and is ideal for kitchens, bathrooms, basements, and more Wire-Free and Sleek Design: No wiring or setup required; only measuring 1" (29 mm) in diameter, this water leak sensor is small and compact enough to fit anywhere and nicely blends into any home decoration; has a 5-year lifespan with 3-year replaceable batteries (included)