Representing the BR air-braked hopper wagon introduced for 'Merry-go-Round' (MGR) trains in the late 60's and then known as HOP AB. It wasn't until the introduction of the TOPS (Total Operations Processing System) computer system by BR in the early 70's that the wagon was recoded as HAA.
Block trains carrying specialised loads are a feature of the modern railway. All Peco wagons feature free running wheels in pin point axles. The ELC coupling, whilst compatible with the standard N gauge couplings, keeps a realistic distance between vehicles and enables the PL-25 electro magnetic decoupler to be used for remote uncoupling.