... 1pcs) 2. AC adaptor12V- CE,UL approval 3. Control unit 4. electric ball valve(1/4",3/8" ... then the valve connected to the central unit • Connect central unit to the AC power,(Power LED indicator ... the water touch the water sensor, the central unit will immediately sound warning tone and corresponding LED light ... if the AC power is OFF, the central unit will still operate, detect water leakage and sound ...