HAA hoppers were produced for the mass transport of coal from colliery to power station in a non stop loop known as `Merry Go Round Operation’, this led to the wagon being known as MGR wagons. Over 11,000 of these 32T hoppers were manufactured for BR mainly at Shildon between 1964 and 1965.

The Dapol model of the HAA features:

• Extremely detailed and accurate body/shell and chassis
• Many separately added fine details
• Sprung metal buffers
• Metal sprung coupling hook and metal screw coupling
• Finely profiled wheels and axles with brass bearing pockets
• Superbly applied livery