20 Pack of Flood And Water Leak Detectors, Whether you own multiple properties or businesses, or you want to give some out as gifts. This is a great deal. Priority Shipping included in price. Water Leak Alarm has a 90 dB alarm with 3 very sensitive sensors below. As soon as Sensors sense water an Alarm will sound alerting you to a leak, saving you headaches and money. Water leak alarm needs a 9V battery to work (not included). Very easy to install.