The access door to the cargo compartment has a latch handle with an opening. The handle is moveable between a closed position, wherein the handle opening is aligned with an opening in a part attached to the door, and an open position, wherein the handle opening is out of alignment with the opening in the attached part. A cable is provided having an end anchored to the cargo door and a free end adapted to extend through the aligned openings, when handle is in its closed position. A magnetic rocker member is spring-loaded toward a magnetically actuated switch and causes a friction wheel to securely retain the free end of the cable. The switch causes the number on a digital counter to change in response to the depression of the button, allowing removal of the cable end. The changed number indicates that the compartment may have been accessed during transit.