Section 208(3)(iii) in The M.P. Motor Vehicles Rules, 1994
(iii)There is attached to the rear of such pole or other thing in such a way as to be clearly visible from the rear at all times a white circular disc of not less than thirty-eight centimetres diameter; and during the period of commencing half an hour after sun-set and ending half an hour before sunrise a lamp in addition to the prescribed lamps on the vehicle so arranged as to show red light to the rear.