Transition wagons, also known as barrier wagons or match wagons, are used to connect wagons that have different coupler types. Flat wagons are typically used for this purpose in the real world since they are usually the lightest wagon available. Aside from coupler differences, the Buffer/Knuckle Transition Wagon is functionally identical to the European Flat Wagon.

Note that AdvTrains versions 2.4.0 and later support requiring that the type of couplers should match when coupling wagons. DlxTrains_modpack versions after 1.4.0 enable that requirement.