All the electronics are built into the head of this Solid-state all electronic float switch assembly. This process takes electricity completely out of the picture in between probes. Otherwise electricity between probes creates calcium buildup, cadmium, nickel, and iron compounds from the electrolyzed stainless steel coming into contact with the liquid its immersed in. Rest assured that each probe is independent from each other and you’ll never face the issues of traditional sensors. The 4 switch single set point multi level activates led lights to tell you which switch is on or off vs. others that don’t have any LED’s. When the low level alarm is triggered from the probes it activates the one of the 4 switches to tell the relay to turn on or off a motor/water pump etc.