The 6 plank wagon was designed to carry 10 tons and was built until the 1907 RCH specification was introduced when a 7 plank 12 ton design became standard. The top plank(s) of the 6 and 7 plank wagons were usually continuous, providing added strength to the body, though sometimes a top flap door was fitted. Wagons with end doors were favoured by collieries, coal factors (wholesalers), exporters and large consumers (eg. heavy industry and gas companies) as the end door allowed rapid discharge by tipping. Side and bottom doors were also fitted so the wagons could easily be used for manual or hopper unloading.