The WalthersMainline HO Scale AAR 70-Ton 3-Bay Open Hopper is based on a design adopted by the Association of American Railroads. The 70-ton capacity car was widely used to haul coal, but was also used to carry aggregates, minerals or ballast. Each model features nine side panels and roadname-appropriate flat or arched ends. The car is ready to run on your HO railroad with a die-cast metal chassis, correct 33" RP-25 turned metal wheelsets and Proto MAX(TM) metal knuckle couplers.