These wagons were originally built in WA between 1967-1971 to transport iron ore from Koolyanobbing to Kwinana. The WO is a standard gauge model in HO which designed by Marbelup Models and comes as a 3D printed body supplied with kadee couplers. The kit does not include bogies, wire or screws.
Decals are available separately here: WO 7 wagon decal set
Assembly tips can be found here: Assembly Tips from Marbelup Models