Abstract: The disclosure herein in directed to aligning devices for aligning a towing vehicle with a trailer wherein the towing vehicle has a ball and the trailer vehicle a socket carrying arm. A pair of magnetic bases having vertically positionable wands are placed one on the towing vehicle and one on the trailer. Each wand has an elastic gromet slidable along its length for retaining a signal flag on its upper side and to permit passage between the wand and the gromet of a plumb line. There are two plumb lines and two plumb bobs which when the lines are vertical and the two plumb bobs positioned immediately above the ball and the trailer socket, the alignment flags will be horizontal so that when the vehicle is backed toward the trailer unit the flags cross then hookup can be effectuated.