Acf 56' 4-Bay Center-Flow hopper - CSX #256436 - N scale. Acf 4 Bay hoppers were designed to carry light density loads like grain or flower, and were used by many railroads. These colorful hoppers will bring added life to any model railroad layout. The Bachmann ACF hoppers feature; NMRA profile metal wheels, needle-point axles, and body-mounted E-Z Mate mark II couplers