for GWR 4-6-0 Hall class, early locos. Nos 4901 - 4980 at 7 mm/ft
(Later Halls had wheels with pin between and reinforced spokes).
A full set consists of 4 x B19 leading, 6 x B327 driving and 6 x B20 tender wheels.
The prototype driving wheel weights are surface mounted plates, and are not cast in.