Presflo and Prestwin were the designation for two types of goods wagon designed by British Railways in the 1950s for the carriage of powdered goods. The Presflo design was specifically for carriage of powdered cement but wagons to this design were subsequently used to transport other powdered commodities. The later Prestwin wagons were designed to overcome problems encountered with using the Presflo design for certain powdered commodities. Both types of wagon were loaded by gravity but unloaded using compressed air.