Features: There are two purposes for connecting the NO and NC ports of therelay: The water pump is connected to the COMNC port to automatically fill the water tower The water pump is connected to the COMNO port to automatically pump water from the water tower Applications: for home water tower automatic water supply system Widely used for Aquarium Fishtank Water Changer System;Fill the water tower automatically ;Automatic pumping from water tower ;Automatic feeding system for poultry and livestock;Farm automatic water supply system Note: The packaging does not include probes (wires). No need to use a dedicated Probe. The probe can be made using household wires for safety reasons. Please use a well isolated DC power supply Specifications: Working voltage: DC12V (DC10-15V) Standby current 9mA Working current 40MA Size: approx 44mmx29mmx19mm/1.73x1.14x0.75in Weight: 19g Load: Support up to 10A/250VAC, 10A/125VAC, 10A/30VDC, 10A/28VDC, 10A/12VDC Note: Due to the problems of lighting effects and shooting angles, there will be certain tolerances in the product, please understand. Please allow 0-1cm error due to the manual measurment. Package includes: 1PC Automatic Water Pump Controller