A 50mm ball can be recognised from a 2 in. ball by the flat on the top which is stamped with a 50, whereas the 2 in. ball ... To buy a towing bracket, ball, coupling and have it fitted and wired up costs in the region of Ap20-30 these days. ... Wiring is not too much of a problem, the seven-pin plug is now standard although there are still plenty of five-pin ones around. ... The figures must not be less than 1 V* in. high and 1 V* in. wide with a minimum width in each part of not less than 5/16 in.