Sighting system for backing a towing vehicle onto a trailer

The driver of the towing vehicle 7 looks into a mirror 9 and steers in reverse so as to align mark 10 on mirror 9 with the centre of pattern 6 in the rear window and with marked portion 12 on vertical member 3 which hangs directly above socket 2 on the trailer 1. This causes ball 4 fixed at the rear end of the towing vehicle to move in a direction to bring it under socket 2 on the trailer. The driver receives an indication that he has reversed far enough by noting when a distinctly marked length 12 on vertical member 3 appears to fill a defined portion of the pattern 6 on the rear window of the towing vehicle. In alternative embodiments, the driver does not use the rear-view mirror 10, or two rear-view mirrors may be used.