This diagram was a 1905 development of the earlier 12T wagons to various diagrams. The body size was increased to 16’3″ long by 8′ wide by 8 planks tall, enabling a 16T capacity. Builders included Cowlairs Works and R Y Pickering. Both steel and wooden solebars were used, and the latter form is the one represented by the kit. All were fitted with grease axleboxes when built, but many were later fitted with the early NBR style of oil axleboxes, and this modification is the subject of a separate kit (NBRD097A). Nearly 6,000 wagons with wooden underframes were built, and around 5,200 were still active at the start of the Second World War. BR inherited 2,829 wagons, but the split between grease and oil axleboxes is not known, although it is likely to be heavily weighted to the latter. It is unlikely that any survived the 1950s. Whilst their main area of activity would have been the industrial areas of Scotland and the Border counties of Northern England, their use further south has been documented.