Hydor Smart Level Controller, Automatic Top Off, ATO Low Voltage And Fully Electronic. 6.5' Sensor Cord. Dual Alarm With Light And Sound To Alert Any Malfunctioning Magnet-suction cup support mount for sensor, also includes cable clamp for cord Insensitive To Surface Movements Of The Waves Versitile. Can Be Used For Any Size Aquarium Or Sump. Adjustable Flow Rate Supply Pump Sold Seperately. Kindly refer user manual and instruction video for reference.