This sensor monitors the flow or position of material in the fertilizer application system. It sends a signal to the cab display or control unit, allowing the operator to verify that the metering process is running correctly. A failed or obstructed sensor will cause a loss of feedback, which may stop the spreading operation or generate a warning without the operator knowing the actual state of the output. The sensor is designed to match the original mounting and electrical connector of the host machine, preserving the correct signal range for the control system.