Contents All of the parts for converting a car from the Märklin Start Up program (cars without coupler guide mechanisms) to Trix Express. Included are. 2 different car floors. a weight. 2 each centering springs. drawbars. and couplers. Two Trix Express wheel sets E258259 are also required. They can be obtained at no charge from a specialty dealer in the wheel set exchange when buying a car new.