Automatic operation. Once its three contactors touch water, it will sound immediately with 85dB loud alarm; No buttons, no programming, just place it where you want to check water leakage; Requires a 9-volt alkaline battery(not included),and normally a new battery can last for 1 year; Use by water heater, sink cabinet, sump pump, washing machine, radiators and more; Made of ABS It is specially designed to float in flood circumstances. Size(Diameter x Height): about 8.2 x 3.2cm (3.23 x 1.26inch ) working voltage: 9v Battery: 9V Alkaline Battery (not included) Alarm: 90 dB Wireless Water Leak Detector Sensor 90 dB Volume Water Leakage Alarm Colour:White Material:abs Package Contents: 1 x Anti-leak alarm Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.