The Resideo Braukmann L5 Water Leak Shutoff Valve automatically shuts off the water supply when a leak is detected. The L5 connects to WiFi to allow remote alerting and monitoring. Can be paired with the L1 Leak and Freeze Detector. When the included sensor cable or a paired Resideo or First Alert WiFi Water Leak and Freeze Detector detects a water leak, this device automatically shuts off the water flow, protecting the home from potential damage. 3/4in ball valve.