Prototype: 12 German Federal Railroad (DB) type OOt Saarbrücken and OOtz 44 Erz Id four-axle hopper cars. Version with very low upper superstructure and brakeman's platform. Some of the cars still lettered for the Brit.-US-Zone. Used to transport iron ore. Standard design pressed sheet metal trucks with welded underframes as reinforcement. The cars look as they did around 1952.
The class 42 heavy steam freight locomotive to go with these cars can be found under item numbers 22224 and 22227 in the Trix H0 assortment.
A display with another 24 car numbers for the Erz Id hopper cars can be found in an AC version in the Märklin H0 assortment under item number 00722, with a reference about the wheel set exchange for DC wheel sets.