Magnetically operated door-open indicator

In accordance with the present invention, the rear roll-up, truck-door indicator is a magnetically operated indicator which is visible to the truck driver by simply looking into the driver's rear view mirror. The invention relates to a rear roll-up, truck-door open-or-closed indicator. The indicator will be located on the outside of the left side of the truck box body. There will be a clear tube placed through the truck box and will extend outside of the body. This tube will be placed at a slight upward angle from the outside of the truck to the inside of the truck box. A colorful indicator piston will be placed inside of this tube. The indicator will be colorful when the door is open; conversely, the indicator will not be colorful when the door is closed.