Truck Door Minder is the world's first and only freight and delivery truck door monitor for roll-up doors. It comes with transmitter, receiver, and smartphone Apps. The transmitter installs in seconds on the rear door. The receiver is placed inside the cab and uses 12V or USB power. Truck Door Minder also is equipped with a rechargeable battery to allow notifications to the driver even when the key ignition is off. Never let the driver get in the truck without knowing the status of the truck door. When the door is in the up position, the transmitter will send the receiver an encrypted signal. The receiver will then notify with a beep and light alert that the door is open. Truck Door Minder also alerts your smart phone with screen notifications.