Originally produced under the Cooper Craft brand this kit has been taken into the Slaters range and is now supplied with Slaters wheels, bearings and turned steel buffers.
During the first 25 years of the 20th century the GWR built a range of standard wagon types equipped with 9-feet wheelbase 16-feet over headstocks steel underframes and oil lubricated axleboxes. Diagram O4 open wagons built from 1902-4 were fitted with folding sheet support rails to prevent tarpaulins from sagging over the load and improving weather resistance. Few of the other major railway companies invested in these fittings, so many GWR opens lost their sheet rails after the start of RCH wagon pooling arrangements, as the better equipped GWR wagons failed to return to 'home' metals! The use of steel underframes ensured these wagons had long service lives with examples still to be found in service after nationalisation.