A device for visually indicating a change in the operational state of a proximity sensor. The device includes a transparent housing having a cavity and a magnet device for generating a magnetic field. In addition, a sleeve is attached to the housing. The magnet device is concealed within the sleeve in a first position to indicate a first operational state. When a target is positioned adjacent the sensor end, magnetic attraction occurs between the target and the magnet device due to the magnetic field to cause movement of the magnet device to a second position within the cavity wherein the magnetic field does not act on the proximity sensor to change the operational state from the first operational state to a second operational state. Further, the magnet device is visible in the second position to indicate the second operational state. The target is attached to a moving element of the valve such as a valve stem such that a change in operational state of the proximity sensor corresponds to a change in operational state of the valve.