Cardboard boxes make up a large number of the items that are moved on conveyors, therefore, it is only natural that there be methods devised to close the ends of boxes while the box is being moved on the conveyor. In this case, a box containing tool boxes is moved with the flaps down. A clamp is used to move the box over two special roller stops. As the roller stop is raised and the clamp on the conveyor moves the box forward, the flap flips down and under the box. When the motion is reversed, the other flap is closed under the box by the second roller stop. This results in a flat closed box, providing easier handling.