Product supply voltage: DC 12V (there are also household AC 220V )Product type: switch type liquid level controller (12V supply voltage, the load can be non-12V or AC load, see the below for wiring)Control motor : within 1000W is recommended.About the probe: The probe is a weak current below 12V. Be to the middle and lower wires, not just two wires. For the probe, you can buy a special probe, or you can a common wire to strip of the wire by 3-5 cm, so it can be directly sensed as a bare wire. Our products do not contain probes Working principle: The relay is closed and closed when the X probe in the upper s leaves the water, and the relay is disconnected when the X probe in the upper s is soaked in the water.Material: PCBColor as shownPackage Contents:1 x water level sensor moduleOnly the above package content, other products are not included.Note: Light and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.