Prevents damage by shutting off the water supply if a leak is detected. Easy to install, no battery or electricity required. The paper string keeps the spring loaded and ball valve open. When a leak is detected the string breaks releasing the spring, which shuts the ball valve off. Device detects 100ml pool of water on the cupboard floor. Detector should be installed on the floor under any water filter system. Simply cut into the 1/4" tubing from your water supply, the detector has 1/4" quick connect push in tube fittings built-in. After string has been exposed to water and has snapped the detector must be replaced. The water supply can be turn back on after the leak has been fixed, by removing the cover and turning on the shut off tap but the whole detector must be replaced to protect from any future leaks. Mounting brackets are supplied.