The level sensor came with the jacks. There are four amber lights for each side of the vehicle on the control pad. When you park, the objective is to lower the jacks until all the light are out. Then it is level.
The unit is rectangular with three adjusting screws that have springs over them. Even when I moved the unit up and down, it had no affect on the light. Also that light seems to stay on even when I know that the coach is high on the right side.
I have the 310/325 Series Leveling System Touch Panel-Controlled.