3200 PRR designed the first quad hopper in 1909 for coke service, the class H21. It had clamshell hoppers and 50-ton trucks. Beginning in 1913 70-ton trucks were applied, creating the H21A class. Over 35,000 cars were built for PRR and the mines it serviced by 1917. Many lasted into the Penn-Central era.
Kit is currently out of production pending a revision.